A Deep Dive into Fallout Shelter

Fallout Shelter shocked many people when it reached the top grossing charts. Many (including myself) have been preaching about the unchanging stasis that exists at the top of the AppStore, and Bethesda came in and changed that completely.

As the smoke cleared, and I watch Fallout Shelter slowly fade from the top charts, I’m left with: “so what did we learn?”

I don’t think anyone can doubt that the brand of Fallout was huge for this launch. It attracted loyal gamers and drove massive organic growth on the AppStore. Every game studio since the launch of Kim Kardashian by Glu has known this. To make marketing on the AppStore affordable, brand recognition is becoming more and more important.

But the marketing aside, what shocked me was the response from players to this game. Here is a game that was developed by a traditional developer, taken a brand many gamers love (as a premium title), and then changed it completely to be free to play. We have seen this many times before ending poorly (see Dungeon Keeper, Sonic the Hedgehog). So what was so different about this launch?

How did Fallout Shelter become a beacon of acceptable free-to-play design for core gamers?

#1 No Arbitrary Session Caps

Fallout Shelter never forces its players to leave. There’s always something positive to do with your vault. There’s no blocker such as energy which says “you must leave now”. But as we’ve seen in previous posts (here and here), having a limit on sessions and progression is absolutely necessary to drive long term retention.

Fallout Shelter employs what I like to call “Flexible Sessions”. The player enters the game, feels rewarded, but the game slowly increases the pressure to leave. Instead of having an abrupt end to the session with energy, Fallout Shelter slowly tweaks the gameplay so you as a player feel smart for leaving.

This is the typical screen the player returns to each time they come back to the game. Lots of rooms with lots of resources to collect. It feels very rewarding to return to the game every time.

Each time the player enters the game there are a ton of things to reward them. Production timers are short, so coming back every 5-10 minutes rewards the player with lots of resources and some occasional level ups of their dwellers. However, the longer the player remains in the session, the less rewarding the game is. This is built intentionally so that players eventually opt-in to leaving the game.

You want to build session design so that the player feels smart about leaving. Not told to leave.


A good example of the game increasing pressure over a session is the “rush” feature. Rushing takes the place of a “skip for premium currency” button which free to play games have. For fallout, the rush feature is no longer a monetization feature, it is a session design feature. In the beginning, the player is trained to continually rush production of rooms. This rewards with faster resource production and bottle caps (a key currency for progression). However, the more you rush a single room, the higher the incident chance will go up. So the more you rush rooms, the more likely a fire or radroach attack happens. The longer you are in the session, the more rooms you rush, the higher risk you have of bad effects. It is strategic to leave and come back later.

Overall the game never really forces the player to leave. Just tries to slowly decrease the value of sticking around. So for core gamers, they never feel like they are being pushed out of the game for no apparent reason, rather they are making strategic choices about when to stay and when to leave.

#2 Disguised Pacing Structures

We can all read from the reviews, forums, and rants that gamers hate timers, pay-to-skip and energy systems. But pacing is the key to long term retention. Without long term retention, a free to play game can’t succeed (more on this here).

So how do we effectively pace traditional gamers?

Disguise the pacing systems to feel different from traditional free to play systems.

Best example of a disguised free to play mechanic is the wasteland mission system. This system is a version of FarmVille’s “plant and wither” mechanic which drove very strong commitment for players to return. Each time a player would plant a crop, the crop would have a limit of how long it was harvestable. If the player didn’t come back before this time, the plant was withered. The player would not get any value from it.

Plant and wither hasn’t been around for awhile because most designers see that player’s really hate it when their first experience coming back to the game is to be punished for not returning. Punishing players at the level of FarmVille these days results in a high churn rate (a high percentage of players leaving the game). But Clash of Clans, Boom Beach and other “Build & Battler” style games have slowly added this punishment back into the toolkit for free to play design. The longer the player is away, the more likely they are to be attacked. When they’re attacked, their precious resources are being stolen.

This fear of losing out on owned items, or “loss aversion”, is a very strong session driver.


Fallout Shelter employs loss aversion with their wasteland feature. Unless the player comes back to the game before the dweller dies in the wasteland, that settler is dead. All those bottle caps and rare equipment the dweller collected? That’s gone too. Of course the player can revive the dweller, but this comes at a cost, which rises over time. “Smart” gamers are going to feel good about scheduling their day around avoiding deaths of their dwellers.

For addressing the core audience, designers will have to reverse engineer common pacing systems and rebuild them to feel something very different. The wasteland feature is an excellent example of how to do this.

#3: Gacha

Lastly, targeting their Fallout player audience, Bathesda knew they needed a fair monetization scheme. The only way to do this is with a Gacha/Card system (more on Gacha here). Fallout Shelter offers no direct purchase of resources. This is the usual method for simulation games. Drive desire for the player to spend when they’ve run out of a specific resource they need.


Fallout Shelter does it differently. Instead of the much-hated resource store, they have a lunchbox gacha system. Each lunchbox contains a random set of cards. Cards can be resources, soft currency, gear, or even rare dwellers. So instead of knowing exactly how much currency you’re going to get, you have the rare chance that you’ll get a rare dweller or rare gear on top of the resources you need. Thus paying for items feels very rewarding versus paying for currencies in other games. You don’t feel like you’re cheating the game (as much) instead you feel like you’re playing the lottery and being rewarded with new toys to play with.

The key that makes this core-gamer friendly is that it is fair because it is luck based. Any player has a chance at the big rare prizes.

It is fair because all players can get lunch boxes from regular play. Playing the game smartly can get you lunchboxes quicker. It also feels fair because the players that pay aren’t really impacting any other player’s experience with the game. Fallout Shelter is not operating in a PvP multiplayer environment. If they were, there would be a lot of pay-to-win criticisms. Because the game is single player, Bethesda had some wiggle room with these pay-to-progress mechanics.

Hearthstone and Contest of Champions has shown that these gacha systems can give lucrative monetization potential. However, the revenue per download of Fallout Shelter over the last few months is much lower than most top grossing games. But when you consider the downloads the game got simply because it took a lighter approach to monetization, this was probably the best choice.

Monetization methods have far more to do with what your audience expects, rather than what would be the best way to make a buck.

The Fall

Despite the all that I’ve praised here, the game ultimately did not sustain in the top grossing. While it initially had the support of the brand, ultimately the game didn’t stick to the top charts because of the lack of content, not pacing players enough and no social gameplay which led to low long term retention.

From discussing with high level players, the game really only lasts for maximum 2 weeks. After this, there is no new rooms, no desire for more dwellers, no new content. No goal to achieve other than optimizing your vault’s layout. For free to play to truly work, your game must last for months (if not years).

So why should you start even considering emulating what fallout shelter built?
Why should we care what core gamers think of our game?

It comes down to your audience, and knowing what they expect and what they tolerate in free to play mechanics. Games for players of mass market match 3 games require different techniques than games for players of fallout.

What fallout shelter has shown is that the core gaming audience can be a big game changer for free to play games. This audience can grow a game overnight that can take over the top grossing charts. This audience is very likely to be the ones playing your game for months, competing at the highest level. Research is showing that the big spenders on mobile aren’t new game players, these are players that have experience playing and paying for games.

Gamers have money and are willing to spend it on games that they feel treat them fairly. So as a developer, if you’re going for a more mid-core or core audience, you have to ask yourself: What did Fallout Shelter teach you?

GDC Europe 2015: Saying No to the CEO

In August I spoke at GDC Europe in Köln about the independent team structure at Wooga. Not everyone knows this, but at Wooga, each team has the final say on all decisions regarding their project. The CEO & Management cannot tell the team what to work on. The team decides on everything including what technology to use, what genre to go after, and how to execute on it.

This talk is about the challenges and benefits of working with this structure for the last 3 years. Its a structure that gives full creative control to teams, but also the full burden of responsibility.

Screen Shot 2015-08-20 at 12.18.44 PM
GDC Vault Video: http://gdcvault.com/play/1022756/Saying-No-to-the-CEO

Slides on Slideshare: http://www.slideshare.net/AdamTelfer/gdc-europe-2015-saying-no-to-the-ceo

Slides for download : AdamTelfer_GDCEurope2015_SayingNoToTheCEO

Multiplayer on Mobile: 3 Approaches

When it comes to free-to-play, ensuring your game has strong multiplayer gameplay is essential to driving long term success. Multiplayer drives strong long term retention for obvious reasons:

  1. Multiplayer gameplay always has the uncertainty of what the other player will do. Each time you play in a multiplayer game, there is an element that you can’t predict, making the game always interesting. Because multiplayer games have this degree of uncertainty, players don’t need a massive amount of content in the game to enjoy it. Compared to a single-player game which a developer has to hand-craft months of content for the player to enjoy, in a multiplayer game, the a developer only needs a fraction of that content. Multiplayer games are far more efficient at pacing.
  2. On top of pacing content, multiplayer focused games always have strong long term retention because you have this feeling of being in a living, breathing community. These games create real social interactions between players. Players build social norming bonds. Playing with real people makes it socially acceptable.

But creating truly social multiplayer gameplay is not trivial on mobile. Creating a well balanced multiplayer is a massive task on designers, add on top the constraints that the mobile platform creates: smaller screen, shorter session lengths and intermittent connections. Because of these constraints, fully synchronous multiplayer has not really seen massive success on mobile except for a few key games: Hearthstone, 8-ball Pool and World of Tanks. Even with Hearthstone, arguably the best at “lean-back” synchronous multiplayer, I know that each time I play I must be completely focused and I can’t quit within that time. The game is not great for handling distractions or allowing players to leave at will. I’ve gotten in trouble enough times for getting stuck in a Hearthstone match when real life needed my attention.

While I’m convinced that games will slowly move towards fully synchronous multiplayer, in the meantime, smart developers will be trying to find ways to create the same benefits of synchronous multiplayer (social gameplay, repeatable content) with systems that are more adapted to the mobile constraints.

Today I’ve put together 3 key ways that developers build multiplayer on mobile currently:

Faked Synchronous

Many free to play games create the feeling of synchronous multiplayer without actually delivering on it. When players are matched up to other opponents, a bot plays in the place of the actual player. Game designers rely on players not being able to feel the difference between a live player and a bot player. Which is difficult, but not impossible.


Contest of Champions by Kabam relies on this. Even though it feels like multiplayer, each multiplayer fight is actually against a bot. By doing this, they cut out problems that come with matchmaking and handling a fully synchronous fighting game with intermittent internet connections.


CSR Racing also does something similar. When you race against another player online, they either use stored ghost of the player or a bot to race the player’s car. Because of CSR Racing’s gameplay, player’s can’t affect the other player’s race. So playing against a bot or a live player is really no different.


But of course, this is the bare minimum of synchronous multiplayer. Just racing against something you can’t effect doesn’t really feel engaging. Real Racing 3 tried to fix this. Taking a recording of another player’s race, they allow you to race against their ghost. During the race, you can bump into their car and send them off course, but their ghost will magically re-adjust to where the original player was racing. Its about as close to synchronous as you can make it.

Overall this approach allows you to have the easiest matchmaking, handles connection stability and players can engage in quick sessions. However, true interactions and the feeling of playing against a live player is lacking.

Simultaneous Multiplayer

Simultaneous multiplayer is something that not many mobile games have used. It originates mainly in browser based games and Fantasy Sports games in the late 90s and early 2000s (see Travian, see Hat-Trick).

Simultaneous multiplayer is done by asking players to prepare their strategy in advance, then both strategies are played out at the same time. With this method, players can come to the game any time before the scheduled turn and make their choices. Players don’t have to be online at the exact same time to interact and compete with each other.


Top Eleven by Nordeus is one of the few games that have implemented a simultaneous multiplayer system. Each match is scheduled at a set time. Each player sets up their team’s tactics, formations, strategies beforehand, then waits for the scheduled match to commence. Regardless if the players are active or not, the game is run.

What’s really nice about this approach is that it provides natural pacing of the gameplay:

  • Player’s feel like the pacing is fair: everyone in the world can only the same amount of actions per day.
  • Session design revolves around scheduled times, building habits and keeping a rhythm

However, this system also leads to a lot of design problems for free to play:
it is extremely difficult to offer monetization in this system without making it feel pay-to-win. Each day each player has the same amount of actions. If payers get more actions than non-payers, or are offered anything that would give them a leg up in the gameplay, it will be felt quickly by other opponents. Matchmaking becomes very important.

Session design feels pretty limiting. After you’ve set up your strategy, there’s not a lot to do before the next scheduled turn. So it becomes a difficult decision for a designer to choose between very rapid turns (anxiety inducing) or a long time between turns (boredom inducing). This system suffers from being too scheduled and not giving players much flexibility if they miss out on a round or want to engage more in the system.

Asymmetrical & Asynchronous

The most popular way to create multiplayer on mobile is focusing on asynchronous multiplayer.

Games like Words with Friends or Draw Something have full asynchronous multiplayer. Each player takes a turn, then waits for their friend to finish their turn. While this is engaging initially, the most games that go for this style of asynchronous have failed on the mobile marketplace. Mostly due to matchmaking, session design and monetization limitations with the game design (see our post on eliminating energy and building social mechanics). But async doesn’t have to be designed this way. They can also be designed as asymmetrical asynchronous.

Asymmetrical Asynchronous games focus on two types of gameplay, usually active and passive, and making each as engaging as possible. When players are active, they engage in one facet of gameplay (mostly the attacking gameplay), when players are inactive, they passively engage in the other facet (defending gameplay). Of course this is shown in the Clash of Clans, Rage of Bahamut or King of Thieves style games.


The key with this style of multiplayer is how to make both gameplays engaging and balanced. Ensure that players must engage in both systems in order to progress. Usually this comes in the form of loss aversion: players need to engage in the defending game to ensure their resources are protected from other players. Players also need to engage in the attacking game to retrieve these resources quickly enough to build and progress.

So far in the mobile world, asymmetrical games have all been constrained thematically to Clash of Clans style “Attacking” vs “Defending”. There’s been some attempts to change up this formula with games like Zombination, where the player can decide to focus more on attacking (zombies) or defending (humans). However for the most part these games fall under the “clash of clones” style game, yet this system clearly has room to grow for new games.

Looking into new ways to apply this formula (Passive vs Active gameplay) to new genres and new gameplay is the key to opening up new opportunities on mobile. King of thieves is the best example I’ve seen to date.


There are other types of multiplayer that can work on mobile.

You can go full synchronous like World of Tanks and Hearthstone, but these have session length problems and critical mass problems.

You can go fully asynchronous like Words with Friends, but this creates critical mass, player inactivity, and further session issues.

You can just stick with leaderboards or other “tacked on” multiplayer competitions, but if you want the real benefits of social multiplayer, you need to tie this into your core gameplay.

Thus far mobile has existed in the middle ground — trying to get the advantages of synchronous multiplayer, but without the constraints that are felt on mobile.

To build multiplayer on mobile there are 3 options :

  • Faked Synchronous
  • Simultaneous Multiplayer
  • Asymmetrical Asynchronous

Each can create strong session design, work with the constraints of mobile, and still feel like living vibrant community. Each have their own problems and their own opportunities.

Deconstructing Marvel Contest of Champions

It’s happened. F2P Mobile is now officially triple A. The major publishers have all put more focus on mobile than on console. (see Bethesda, Nintendo and Konami)

Now we are also starting to see high budget games climb on the top grossing charts.

If you still believe that the AppStore can still have indie success on the Top Grossing, the stakes are rising. Games from now on will need significant investments in their visuals on top of having a strong economy design to succeed.

The proof of triple-A F2P is “Marvel Contest of Champions” by Kabam. Showing their recent commitment to working closely with Hollywood, they’ve brought both AAA visual standards and a strong license to mobile. As a result the game has been downloaded by over 30 million people and taken a dominant spot in the Top 25 grossing:

Screen Shot 2015-06-24 at 6.22.35 PM
But is this game just all glam, but no substance? Can Marvel sustain in the Top Grossing?

The Pitch

Kabam’s approach for Contest of Champions was clear: Take “Injustice: Gods Among Us” and, apply it to a new license. On top of having the license, take learnings from Kabam’s other games and improve the economy design, multiplayer, and ensure that events are strongly tied to its core.

Its a simple premise, but Kabam’s secret formula of events, multiplayer gameplay and monetization is a powerful force. They’ve proven this before with the Hobbit’s mobile game and the Fast and the Furioius mobile game.

Screen Shot 2015-06-24 at 6.26.05 PM

Injustice: Gods Among Us was a game released in March 2013 by DC Comics and Warner Brothers. Its essentially a very simple fighting game at its core with a collectible card game as its meta.

Both Injustice and Contest of Champions are similar to Idle games where it really gives players a “bait and switch”. Based on the screen shots you’d think this was the next Street Fighter or Mortal Kombat. But after the first battle you quickly get introduced to the true intention of the game : collecting the characters and upgrading them. You came for the 3D fighting mechanic, but are quickly hooked in the long haul to collecting the characters.

The Core : Back to Basics

Comparing Injustice to Marvel Contest, Marvel has simpler controls, easier strategy, and much shorter battles. Injustice focuses on building up a combo enough to do a quick-time-event (“Swipe to knock down opponent”) whereas Marvel is more about building up a sustained combo of attacks of choosing whether to jab (which can be defended) or go for a heavy attack which can break defenses.

Fights are much shorter because they’ve cut out the 3v3 battle. Its 1 on 1 like original fighting games with victory based on the first KO.


Overall I believe the changes make the game better for mobile. Its easier to play and the fights are quicker. This allows players to complete sessions in less time and spend more time in the metagame. However, moving from 3v3 sacrifices some of the strategy in the battle. As a result battles quickly grow pretty tedious, which puts more pressure on the metagame to keep the strategy.

So how did Marvel fill the gap in the Meta?

Unlike Gods Among Us, Kabam also chose to focus on elemental types. This adds more strategy to choosing which hero you bring to different fights. Also to make sure that the simple 1v1 fights don’t push players to collect and invest in only 1 hero, they added elemental types which push players to collect heroes of each element.

Each element has a strength and a weakness. So each time the player enters a match, they run the risk of facing up against an enemy which is their weakness. This adds strategy to choosing who you bring along and making sure you have a spread of different strong heroes for each type.

1KaLbZd (1)

Bringing this all together, Kabam really pushes players to be strategic outside the battle. So when you’re playing a online match, players are invited to strategize about which fighter they want to play against an opponent:


Note here that the Scarlet Witch shouldn’t be paired up against Hulk. The player  should try to find a better matchup.

The Meta : Gacha for the West

This is really where Contest of Champions gets interesting. At the metagame layer, the game delivers on the licensee’s strengths. There are a ton of different Marvel heroes to collect, each of which has their own, stylized 3D model.

marvelcoc1 (1)

Each character feels unique. Each character looks beautiful. As a fan of Marvel, you’re really driven to collect your favorite heroes. However, this is where the monetization and retention come in. To get your favorite hero, you need to get lucky in the Gacha system.

This Gacha system is embodied in the Crystal Vault :


Crystals are a currency that is used to give a random reward. Crystals are earned through timers (daily, every few hours), through play (multiplayer or single player) or from purchase. Each time the player completes one of those actions, they are pulled into the Crystal Storage screen. From here, they can open up a random reward within: A resource or sometimes a new character. Here is an example of a player opening up a crystal:

These Crystals are the most important design decision that Kabam made.

There are 3 reasons for this:

#1: Each time the player earns a crystal, they are brought back to the Crystal Vault

Each time they complete the actions needed for the crystal, they are brought back to the storage area. Each time they are reminded of all the other options they can purchase, and all the other means to progress. Players know that in order to get heroes, they need to earn crystals. In order to earn crystals, they need to pay or play.

#2: Each Crystal is a Lottery


Each crystal gives a chance of what you want. No crystal ever gives defined rewards. Want that cyclops? Well that’s the top prize in this crystal, so buying the crystal will not guarantee you earning Cyclops. This is gacha done perfectly.

Gacha works because in the beginning players can purchase these gacha packs (crystals) and get great content. Each time they open a crystal they get a brand new hero they’ve never seen before. As time goes on, as a designer you introduce mechanics and promote content that drive players to want rarer and rarer star players. So a player wanting a 4 star rare Cyclops is going to have to purchase many, many gacha packs before they get exactly what they want.

This should be taken with some fairness though. You want to make sure that player’s don’t feel cheated when they spend money. So similar to Hearthstone (each card pack includes 1 rare), Contest also guarantees a certain star tier with each crystal that is paid.

Unlike Injustice: Gods Among Us and Mortal Kombat X (a recent release by Warner Brothers) Kabam chose to offer no direct purchasing of heroes. In Injustice, players can look at the store of all the heroes in the game and directly purchase the hero they want. In Marvel, players have to use Crystals to collect all the heroes they want. This design is more similar to Japanese games like Puzzles and Dragons, and has been a lucrative business for them. By cutting out the direct purchase and going for a more pure-Gacha system like Japanese games, they’ve maximized their revenues.

#3: They offer no direct purchase

Injustice allows players to purchase characters directly. This is a costly mistake for Warner Brothers.
Injustice allows players to purchase characters directly. This is a costly mistake for Warner Brothers.

Never allow player’s direct purchase of the content that they want in a Gacha system

Allowing players a direct purchase of the hero they want is a hit to your retention and monetization. You’ve given them the end game content for a single quick purchase.

You can see this also when you compare Mortal Kombat X to Contest of Champions. Mortal Kombat X was recently released by Warner Brothers. Arguably each game is well designed and looks beautiful, but on a Total Revenue to Total Download ratio, Marvel comes out well on top. Kabam is simply far better at monetizing, and offering no direct purchase improves this metric.

Gotta Collect ‘Em All

But the strength of Gacha lies only when you’ve added an additional layer: Rarities. In order for Gacha to work, you need to drive desire to get the absolute rarest items. In the beginning as a player it is alright to get a 1 or 2 star spider man. It feels good to get these heroes. But as you play, you quickly realise that this spider man isn’t going to cut it — you need to play your chances at getting the rarest heroes.



To do this, Kabam added Star Tiers to their heroes. Each hero can be found in 1 star to 5 star forms. The higher the star rating, the rarer the hero. Having a higher star hero increases their base stats, exponentially increases their potential highest level, and adds passive and active special abilities during the battle. All 3 of these are important to monetization and retention.

Having strong base stats makes the hero feel powerful immediately versus opponents. Making sure that Rare monsters immediately feel good to purchase and easy to dominate opponents with is crucial to drive first time purchases.

Exponentially increasing the maximum potential also increases the amount the player must invest their time and energy to reach the hero’s maximum potential. The higher the star rarity, the more time the player must spend to upgrade the hero to their maximum potential.

Players must collect ISOs to upgrade their heroes.
Players must collect ISOs to upgrade their heroes.

For players to upgrade their heroes, they must use in different strands of ISOs. ISOs come from actively playing (mostly) so in order to fully upgrade your amazing 3 star champion, you have to collect ISO.

This is essential for Long term retention. This mechanic nudges players commit to training their heroes to receive their full benefit. Without this exponential growth, players would pay for the best hero then forget about actively playing in the game.



Lastly, Adding Passive and Active special abilities in the battle gives visual feedback to the player that what they are doing (collecting rare heroes) is worth it.

Heroes that are 3 stars or more have an extended special ability bar (as shown above in the bottom left). When the player fills up this meter, the hero shows a unique animation and does a lot of damage. You can only trigger this ability if you’ve got the 3 star or higher version of this hero. This is very important to ensure that players feel rewarded and powerful for getting the highest heroes.

Just increasing a virtual number is not rewarding enough for players. Eventually you’re going to have to give players real visible rewards for getting the rare content.

In Summary

Kabam’s Contest of Champions decided to focus their innovation on outside the battle, in the Meta. The Meta for all games is what drives long term retention and strong monetization. This paid off for Kabam.

They focused on creating a pure Gacha system, stripping out elements from Warner Brother’s Injustice: Gods Among Us that was conflicting with what they know to drive strong free to play design:

  • Simpler, shorter battles for better sessions
  • No direct purchase of heroes
  • Engrained crystals into the core game loop
  • Deeper Star Tier system to create more reasons to purchase
  • Elemental system to promote collection of heroes

As a result, Kabam have a top performing game.

To be Continued…

Marvel Contest of Champions innovations and design insights don’t just stop at the Gacha system. Rather than overwhelm you, I’ll put this one on pause for now. Next up I’ll focus on Multiplayer and Session Design.

Stay Tuned!

I’m speaking at GDC Europe 2015

As was announced on Gamasutra, I’m speaking at the upcoming GDC Europe Köln in August:

Gamasutra: Come to GDC Europe for cutting-edge studio leadership advice

My topic is “Saying No to the CEO: A Deep Look at Independent Teams”. I’m looking at the management practice of fully autonomous teams in a large studio. From my experience at Wooga, I’ll be discussing both the benefits and drawbacks to working with an independent structure.

– How to construct an independent team culture that works
– What benefits you can expect from an independent culture
– What the limitations are of this culture, and what problems to expect
– What requirements there are to company culture and employee personalities

Looking forward to the event! Contact me on twitter or email if you’d like to meet up while I’m there.


Is Supercell’s Smash Land too Simple?

Supercell’s most recent soft launch is called “Smash Land”. It’s been in soft launch phase in Canada and Australia since March 31st 2015 (About 2 months from this post). There is no doubt that Supercell’s soft launches are huge news for the mobile free to play industry. Supercell is notoriously picky about what games that make it to soft launch. Each new game goes through rigorous internal feedback, and only the best games survive. The games that hit soft launch are games that Supercell genuinely believes have a shot at the Top Grossing charts.

Smash Land is based on “Monster Strike”, a massive mobile free to play game in Japan. In December 2014 it took over Puzzles and Dragons’ top spot in the Japanese charts. Similar to how Supercell started Clash of Clans with looking at Backyard Monsters, Supercell now looks to simplify the design of Monster Strike so that it could work in the Western markets. But in Supercell’s simplification of a game that performs so well in Japan, has the game stayed intact?

Has what remains kept what is required to be a successful game?

Smash Land’s Core Battle

Supercell decided to keep core battle game the same as Monster Strike. The core battle mechanic is a Physics-based RPG battle. Almost like a game of pool, the game is mostly about predicting how balls on a flat surface will bump and move to create a preferred outcome. In Smash Land, the game is about lining up one of your characters so that it bounces between walls, enemy characters and your own characters as many times as possible. The player then collects up to 10 different heroes, each with their own special ability. For an overview of the mechanic, watch this video:

Overall the core battle feels smoother, cleaner and is much easier to understand than Monster Strike. Each character feels unique because of their special abilities which feels great.

The gameplay is very strong for a mobile F2P game. Its easy to pick up and understand for any player. The feeling of skill is strong — I can predict a few bumps and feel smart about setting up strong combos. On top of this, because of the nature of physics, Luck comes into play. Like Peggle, physics is usually pretty easy to predict after the first shot, but after the first few collisions it becomes almost impossible to predict the outcome. As a result each move can result in some “Post-Action Luck” which is critical for casual games.  Players feel smart and each shot is unpredictable.

Overall they’ve taken the best bits of Monster Strike and applied it to a more focused experience. It’s a great battle system that is easy to get addicted to.


Outside of the battle, players can also engage in upgrading their heroes stats. This is really where Smash Land departs from Monster Strike.

Monster Strike contains far more variety of stats for each character:


Just comparing these two screens you can see the dramatic comparison between the games. Its much easier to understand Smash Land compared to Monster Strike.

However, at what cost is this simplicity? In Smash Land the major differences between the characters are special abilities and their health to damage ratio. In Monster Strike, the team you bring into battle requires far more strategy as you progress in the game.

You need a balance of elemental types on top of ensuring you’ve got strong special abilities that are complementary. My guess is that while Supercell’s game clearly scores points for understandability, it will seriously limit the long term replayability of the game compared to Monster Strike. Players just won’t have nearly as much to strategize about in the long run.

Smash Land also departs from Monster Strike in how upgrades are handled.


Heroes are upgraded with gold and time. So the player collects gold from playing matches or collecting them from treasure hunts, and turns this gold into upgrades to their heroes. The cost of each upgrade escalates very quickly. As a result, the game really starts to require many, many battles before you can afford a single upgrade.

Smash Land’s system is far simpler than Monster Strike. Monster Strike takes cues from Japanese Gatcha games like Puzzles and Dragons. To upgrade your heroes you must collect hundreds of characters and consume them to give experience points to your heroes. For a great overview of Gacha, read here.

Leaving the Gatcha system out for Smash Land is a big risk, what remains is a far too simple economy that quickly becomes a grind.

Monster Strike’s system with consuming & collecting monsters has a massive advantage in the long run compared to Smash Land. Instead of just 10 heroes, Monster Strike has almost 1000 collectable monsters in the game (source). With this massive set of monsters, they have created a system where players have much more excitement for the long run.

As I’ve spoken about before, to alleviate the feeling of grinding it’s all about creating random spikes of progression. Similar to games like Diablo you need to find ways to add luck to your progression. Ensure that each battle can result in a lucky outcome which could dramatically increase their pace of progression. In Diablo this could be finding a legendary weapon on the ground which makes it a breeze to beat the enemies following.


In Monster Strike, instead of powerful rare swords, players can randomly get awarded rare monsters from the gatcha system. The player now feels lucky, like the game gave them something for free that should have cost them real money or a lot of time. Because the player got this rare monster, they can rush through previously hard levels and feel great.

Overall the rate of progression may be slow, but because there are these moments where progression randomly spikes, players are far more likely to engage for a long time.

This variable progression is missing in Smash Land. To progress, you must upgrade your  heroes in a linear path. Each victory gives you a calculated amount of rewards. The cost of upgrading a hero grows each time.

Overall, with only 10 heroes and very limiting upgrades, the metagame is just too simple. I have the same heroes as everyone else, the same upgrades as everyone else, so there is no moment where I feel like I’ve got a really unique set of heroes that are more amazing than my opponents. Without this unique feeling, it is hard to get attached to my characters or get attached in the long run.

Desirable Stats

Smash Land removed plenty from Monster Strike when they simplified the heroes/monster collection structure. But regardless of how many collectable characters you have in your game, if you want players to engage in an upgrade system you need to ensure that those upgrades are desirable.

IMG_0108 (1)

In Smash Land my drive to upgrade is very weak. The battle overall feels very Skill & Luck driven (as I described above). The outcome of battles has more to do with getting repeated bounces over how much each player’s heroes had levelled up. In many cases I won with far fewer levels than my opponent, or I lost at the hands of an opponent that had far fewer hero levels than me. This translates in less player demand for upgrading their heroes. Instead of having a strong desire to have the strongest possible team, players will blame victories on their skill or luck and will more likely be content with their team as is. This is a difficult balance to get right in any game. For more on Stats vs Luck vs Skill, read on here.

But for this game, where its whole monetization plan is dependant on players upgrading their characters, Stats must take more precedence in the outcome of a battle.

If the player has a decreased desire to upgrade their heroes, then this will break how the game monetizes. Hero upgrades are at the core of how this game makes money. Players grind for coins (or spend money), on top of have long timers (8 hours or more) to upgrade their characters. After spending money in the game, speeding up the upgrades all of my characters substantially, I really didn’t feel any more powerful in the game. I lost subsequent multiplayer battles, and was now facing an even higher upgrade cost for my heroes. In the end spending money in the game really just didn’t feel worthwhile.

Overall Thoughts

If this wasn’t launched by Supercell, this game would never have gone under so much scrutiny. The game on its own is polished, fun to play, and ticks all the boxes for being a successful free to play game:

  • Strong Pacing of content
  • Multiplayer gameplay to provide long tail retention
  • Guilds to bring players together without requiring Facebook
  • A simple game mechanic that’s easy to pick up and play, hard to master

But when you put them all together in this game, the metagame is too simple:

  • There is not enough variety or strategy in choosing heroes
  • Upgrading quickly becomes tedious and a long grind
  • There is not enough desire to upgrade your team to compete at the highest level

So how will this do on the market?

So far it seems Supercell is keeping this game in a quiet soft launch. Comparing this soft launch to Boom Beach, by 2 months Boom Beach was higher in both the download charts and grossing charts within Canada (source:AppAnnie). That points to Supercell keeping the marketing costs & number of new users down for the time being while they improve the game. Supercell is very rigorous with their soft launch games. Just last year they released “Spooky Pop” which failed to hit their targets. As a result they decided to cancel the game.

Can Supercell turn this game around during the soft launch? I think it will be difficult. They cut so much away from what made Monster Strike work, its hard to see if small feature additions will be able to rebuild what’s necessary. It will only happen if they completely rebuild their Hero progression systems.

I think Smash Land should be an example for all future mobile game designers. Simplicity can open up to wider markets, but the focus on Free to Play must be on long term retention, not the widest audience. Game designers must strive to create enough longterm depth in their metagames, or else they will fail.

Addendum (02.07.2015) :

According to VentureBeat Supercell has decided to shut down Smash Land.

The team clearly worked very hard on the game and created a wonderful product. This just reiterates the fact that creating hit games on the mobile AppStore is extremely difficult, even for the best developers.

I look forward to what Supercell constructs in the future!


Why Games Fail: Pre-Production

Every project that I’ve seen fail, the team always says one thing in their Post-Mortem: “We should’ve done more Pre-Production!”

It is the tell-all excuse. Teams always place the blame on the Pre-Production phase.

Why didn’t we figure this out before we went to Production? Why did we rush into production when there was so much left to solve? How did we not see the monster this game would become?

How do we solve this? How do we get to the point that we avoid projects going into Production that are just going to explode in scope or the design falls apart?

Mark Cerny’s “Method”

Back in 2002 during a DICE Summit, Mark Cerny, a Producer on various Naughty Dog projects, presented “Method”. Mark Cerny offered a solution to the problem that faces complex game development: a better approach to Pre-Production.

Mark argues that most games fail solely because they haven’t done Pre-Production properly. Production is not the time for teams to be discovering what will make them successful.

This was presented in 2002. Game Development has changed drastically since then. For instance, developers now can release at the press of a button. We now use soft launches and analytics to test games while live. We don’t have the weight that comes with having to launch a physical product. However, despite the benefits of modern game development, much of what Mark speaks about still applies. Many projects fail, pointing back to a failed Pre-Production.

So what can we apply from this talk to modern game development?

“You will spend a million dollars before you know what your game is…”

There remains two distinct phases in Game Development: Pre-Production and Production. Pre-Production is for when you are “capturing lightning in a bottle” a.k.a. identifying what makes you different, what will make your game a hit game. Production is for when you know you have a hit, you just need to deliver it.

The goal of Pre-Production is to reach a state which you are confident that your game will be a hit.

Pre-Production is also about defining key variables, economies, mechanics enough such that you can start producing final content for your game. Yet to reach this ideal point is extremely difficult.

The Journey to Production
The Journey to Production

Pre-Production phase can last a long time, and can’t really be tracked. Finding how to pull all the pieces of a working game together into a publishable package is a very elusive process that can take months or even years. Free-to-Play games in comparison to traditional PC games I would argue have more moving parts. Session design, economy design, social mechanics, elder game design must all come together on top of having your core gameplay completely nailed down. 

My rule of thumb is Pre-Production for free-to-play games should last anywhere from 3 months to a year. It will take you at least that long to properly prototype & iterate your metagame and economies. If you aren’t taking this much time, then you’re either cloning a game (in which you don’t need Pre-Production nor a conscience), or you aren’t spending enough time nailing down your game’s design. How long you need in Pre-Production is dependant on the team’s experience level. If you are creating a game within a genre you know, this can take 3 months. If you are exploring genres you have never created in this can take at least a year, if not more.

Pre-Production for free-to-play games should last anywhere from 3 months to a year.

A whole year on Pre-Production? That seems ridiculous! Yet in reality, spending this much time in Pre-Production pays dividends during production. If you reach this ideal — having a clear definition of what makes your game unique, all game variables are defined and your metagame is nailed down, Production becomes near trivial. When you scale up your team, you will spend far less time in Production. So instead of Production taking years on a game with 20-30 people, it takes just 6 months. You will avoid many pivots that happen in production, when the cost of change is very high.

So be prepared to spend a million dollars in Pre-Production. It will be worth it come time for production.

“A Publishable Prototype”

The goal of Pre-Production is to define what makes your game great. Prove to yourself, your team, and all stakeholders that this game will become a success. The best way to do this is to produce a complete prototype which proves your game is great.

What does a complete prototype look like? It is an ugly, cheap version of your game that is playable on device. But it has the full game loop: all the economy systems, all the gameplay mechanics, and everything that you think is absolutely required to prove that your game will become a success. All in one prototype. It should feel as close to the final game as possible, while being as cheap as possible to produce. Art can help, but should not be the focus.

I choose a complete prototype over a bunch of small prototypes because game design is extremely interconnected. To truly prove how your game will ultimately feel, you have to put it all together. The effects of a design decision are not always apparent until you play with the systems interacting with each other. This can take more time than necessary, but this has proven time and time again to identify unseen problems in my own game design.

Complete prototypes identify problems that separate prototypes can’t.

The team’s role during Pre-Production is to produce this complete prototype. Build the experience of the final game as quickly as possible. You will find that through many iterations, what you initially felt was going to make the game successful changes with each release. This is natural and necessary. When you build a complete prototype that feels as close to the final version as possible, many issues arise that you typically wouldn’t find out about until close to launch. The key with prototypes is to build your game into the monster it will become as quickly as possible.

But when is this prototype done? When are we ready for Production?

To define how to reach Production, I create a checklist. This checklist provides a vision about what we must prove before we enter production.

To create this checklist :

Conduct a Pre-Post-Mortem, imagine how your Project could fail. Define what the biggest risks are for your project:

  • Define what must be amazing in order for your game to be successful.
  • Define what can kill the project you if you get wrong.
  • Define what assumptions must be confirmed before you start producing final content.

When you feel confident that you’ve done all you reasonably can to hit each of these points, then it is time to move to Production.

Just keep in mind:

“Your Product will not miraculously get better in Production”
If there are core design problems in Pre-Production, don’t expect them to go away with simply adding more content in Production.

“A cancelled product is not a reflection of the team’s ability.”
The goal of Pre-Production is to do everything possible to kill your game — not to protect your game from any chance of failure. As a team you must eliminate risk and spot when the risk is just too high. Killing a game in Pre-Production needs to be accepted. Killing a game saves money, time and years of emotional strain on any team member involved. A failed prototype is a celebration.


The keys of a strong Pre-Production are:

  • Make time for exploration and defining what makes your game great. Give at least 3 months to 1 year depending on the experience of the team.
  • The team must be focused on delivering a complete prototype which reduces as much design risk as possible.
  • To enter Production, you must define your design risks. Create a checklist of these risks and ensure they are fixed before entering production.

As massive scale 3D productions become the norm, a strong Pre-Production process will become far more important.

Why you should care about Idle Games

Idle games are an exciting new genre that I expect to expand greatly in the coming years on mobile. Idle games, Clicker games, or “games that play themselves” is a baffling genre. Inexplicably these games are dominating many of the popular flash portals and shooting up the charts on mobile. Make it Rain by 337 Games, Tap Titans by Game Hive and now AdVenture Capitalist by Kongregate have all shown that this genre has a rightful place on the AppStore.

But why is this genre so popular? Why does this genre even exist? Why even discuss games that people don’t really play?

Idle games have risen on mobile because this is a genre that is perfect for modern mobile free-to-play design. The mechanics of idle games create perfect mobile sessions and drive strong long term retention.

What is an Idle Game?

Idle games, sometimes called Clicker or Incremental games, are games which are all about management of revenue streams. Similar to simulation games, their main differentiator is the focus on revenue growth decisions.

For some examples:

Cookie Clicker : http://orteil.dashnet.org/cookieclicker/
Cookie Clicker : http://orteil.dashnet.org/cookieclicker/

Cookie Clicker is the best example of an idle game. Each time you tap the cookie, you gain 1 cookie. You use cookies to purchase upgrades. Upgrades increase either the rate of tapping the cookie (now you get 2 cookies per click!) or increases the rate of cookies generated automatically (Grandmas will make 1 cookie per second). These automatic cookies are generated whether you are tapping or not. They are generated even if you’re away from the game.

On paper this sounds too simple to be fun. But try for yourself. The simple act of purchasing an upgrade always feels great. The growth curve is so fast it gets very addictive, very quickly.

Progress just for the sake of progress is fun. Even if it only means a virtual number increases faster.

Rate of resource generation is the core of the game. But an economy that inflates so quickly with a single currency has flaws. Very quickly, the game’s upgrade costs skyrocket. Starting off with nice low numbers the game quickly skyrockets into costs of trillions just a few sessions in. Most designers would cringe at this type of growth curve. What kind of player wants to worry about numbers in the trillions? In AdVenture Capitalist, your costs will eventually reach more than 1 Tretrigintillion (10 to the power of 102). Yet, players love this. Progress always feels good. Players playing for long enough to reach these ridiculous numbers feel like it is a real accomplishment.

As a result, Idle games have claimed 3 of the top 10 most played games on Kongregate (source: here). There are even Twitch channels dedicated to watching a computer play a game itself. Inexplicably, this genre has seen incredible growth.

Regardless of your stance of whether or not this is a “real” game genre, the mechanics in Idle games are perfectly realized for mobile. Idle games can teach mobile game designers a lot about creating a game that has strong session design. Idle games are so strong because:

  1. It always feels good to come back.
  2. Sessions naturally ease the player to leave
  3. The mechanics ease the player from micro to macro gameplay

#1: It always feels good to come back

Many mobile games suffer gameplay mechanics that feel punishing on returning to the game after leaving for a few days.

In FarmVille: crops wither. If you do not come back to the game in time, your crops are worthless. In Clash of Clans: resources are stolen. The longer you are away from the game, the more likely a majority of your precious resources are stolen. Your rank on the leaderboard could be lowered. Your Clan becomes upset that you haven’t donated enough troops. These mechanics are all strong at driving reasons to come back, but also creates reasons for players to quit.

Idle games don’t suffer from this problem. Each time the player returns to the game, they are left with a massive stockpile of cash. It always feels like a bonus that they left the game. If a player leaves for a day, a week, or a month it only increases the amount of currency in their stockpile. In most economies this would be troublesome. Not in Idle games. Because the growth curves are exponential, leaving a game to infinitely generate a low income rate is absolutely fine.

Revenue Growth Player A B
Player A grows faster from Day 1. Player B waits until Day 7, but gains a massive stockpile.

For example, lets take 2 players. Player A comes back every day. Player B skips a week of play. Both players are generating 1 million cookies per day at this point in time. Player A, the active player, returns day 2 and receives 1 million cookies. Player B, who skipped the week, returns to have 7 million cookies. Player B can clearly purchase far more upgrades than Player A. Player B actually feels very rewarded for leaving for so long — they are rewarded with a very long session which they can purchase many things. However, comparing the growth curves Player A purchased many upgrades on that second day. So Player A by day 2 is already at a new growth rate of 10 million cookies a day. Player A is clearly growing far faster than Player B, but both players (because its a single player game) feel they made a smart choice. Player A is rewarded with faster progression. Player B is rewarded for waiting so long. It always feels good to return, but returning more often gives you faster progression.

Mobile games should strive to create this feeling. It should never feel like a punishment to come back to the game.

Players should be reminded that coming back often is a benefit, but coming back at all is always a bonus.

For this reason most farming games have shifted away from FarmVille’s model. Instead of withered crops, there’s low storage limits. In Clash of Clans, they incorporate shields and enforce looting limits to make sure players dont feel that not coming back feel too badly.

#2: Sessions ease the player away

Coming from my previous post on Flexible Sessions, the perfect mobile session finds a way to naturally push players out of the game. This is necessary for pacing and long term retention. Strong mobile games give strong reasons to come back (see above!) and strong reasons to leave the game. Idle games have mastered this natural prod of players out of the game.

Offering lots of purchasing options creates the session design. There is always something to purchase, but eventually the smart choice is the one where the player must wait.
Offering lots of purchasing options creates the session design. There is always something to purchase, but eventually the smart choice is the one where the player must wait.

As Idle games push players to invest in automatic revenue generators (ex. Grandmas in Cookie Clicker) over manual revenue generators (manually tapping on the cookie), players inevitably will reach a point in the game when they just have to wait. The player can purchase small upgrades fairly rapidly, but they know to make the next big leap of progression its smarter to purchase the more expensive upgrades. So, they leave the game feeling smart about their decision.

This is the exact point which the player, themselves, have opted-in to leaving the game. Naturally, the game has prodded the player to leave. Mobile games must strive for this. Create a situation which the player feels smart about leaving your game. Idle games have even managed to do this without timers, without social appointments or any other tacked on system as discussed in Player Commitments.

Create a situation which the player feels smart about leaving your game.

#3: It eases the player from core to meta gameplay

The first experience of a new player is very simple. In Clicker Heroes: A player just madly taps an enemy monster. In Make it rain: A player flicks heaps of money into the air. The first experience is addictive and immediately fun. Its obvious how to get better – tap or swipe faster. Players quickly master this mechanic and it feels natural. However, this mechanic’s interest quickly burns out. After the first few sessions, players are quickly tired of having to manually collect.

This is when the game offers a bait and switch. You came for the simplicty of tapping, but what you’ve been given is a game that is all about managing resources and upgrades. Players shift from tapping to managing which upgrade to purchase next. This clever switch means players that would have been burnt out from the simple mechanic are now thinking about long term decisions in the game. Which upgrade is the best value? How do I optimize my growth?

Mobile games must master this bait and switch. Players expecting to come into any mobile game will expect some core gameplay that mimics what they’ve played in the past. Playing bejeweled for Candy Crush, playing command and conquer for Clash of Clans, or platforming for King of Thieves. However, as a free-to-play designer your job isn’t to just hook these players with fun intial mechanics. You need to find ways to retain these players for years. The best way to do this is to switch the player from focusing on second-to-second core gameplay (tapping cookies) into longer term decisions (optimizing progression). Idle games clearly show a blueprint of how to accomplish this, regardless of the core gameplay.

Looking to the Future

Idle games are big and going to get bigger.

Anthony Pecorella gave an excellent talk at GDC 2015 on Idle Games summarized here. Clearly with the success of AdVenture Capitalist, Tap Titans and Make it Rain, more developers are taking notice.

The genre is ripe for innovation. Recently CivCrafter came out. A take on the idle genre with multiple resources and battles. Tap Titans has shown that the genre can apply to the auto-rpg genre. I believe that the progression systems in these games can really be applied to any genre. Replacing the core game play with a puzzle mechanic, an RPG battle mechanic, a Simulation theme, Arcade gameplay are all possible angles.

The key is to design the bait and switch: give the players the game play that is addictive and fun in the beginning, but eventually nudge them into purchasing the automatic resource generators. Players can then make the choice between grinding the core gameplay, or leaving and gaining the benefit just by waiting.

Get ready: the future will be all about games you don’t play.

GDC 2015: In it for the Long Haul

Recently I spoke at GDC 2015 in San Francisco with my colleague Sebastian Nußbaum. We conducted a talk called “In it for the long haul: How Wooga boosts long term retention”. We were both amazed by the response. The GDC feedback was extremely positive: we ranked #1 of all F2P talks in the GDC Summits.


To view the video of the presentation, you will need GDC Vault Access. You can view it here. The slides of the presentation can be visible here.

We discussed the importance and difficulty of delivering strong long term retention. My half of the presentation focused on creating long term retention during prototyping/pre-production, while Sebastian discussed how they delivered long term retention through Narrative design in Pearl’s Peril.

Just as a summary of my main points:

  • Long Term Retention is the biggest differentiator of the Top games to the rest of the F2P market
  • Long Term Retention is more important than monetization or broad audience appeal

To create long term retention:

  • Create a long term goal or aspiration
  • Create mechanics that encourage players to invest in the long term of the game
  • Create session design that both pulls players in 6+ times per day, as well as paces players naturally in the progression
  • Create social mechanics that require players to rely on others to play at their best
  • Understand the cost of content production by your team vs content consumption by your consumers. This must be a healthy ratio.

To test long term retention of new concepts, during prototyping focus on creating a game that lasts for 1 month of fun.

Stop any game that doesn’t show it can scale to one month of fun. Games that struggle at this point have a dangerously low chance of figuring out long term retention during production.

Deconstructing King of Thieves

Let’s take a deep dive into ZeptoLab’s latest game: “King of Thieves”. Launched in February 2015, this game has piqued my interest. While not on the top spot yet, the game’s bold design deserves a look.

In my opinion, this is a game that deserves to be successful. It feels unique and has all the elements that make up a top grossing game. ZeptoLab has taken what works in simulation and strategy games, and applies this to a totally new genre and a completely new target audience.

This approach is what I feel more new game designs should do to be successful on the AppStore.

The Pitch

The pitch for King of Thieves is “Super Meat Boy” combined with “Clash of Clans”.

Untitled drawing

The core gameplay is a one-button platformer. Your Thief (the little cute black shadow) automatically runs left or right. You can tap to trigger a jump in the current direction. You can also jump off walls to reverse the players direction. ZeptoLab has managed to give classic platformers a mobile makeover. With one-touch controls it feels native on mobile. With simple rules, it feels expressive and gives players plenty of options. The gameplay is simple and is very transparent about what you did wrong each time you die. This creates very addictive core gameplay. 


The object of each level is to reach a treasure chest. Go from “point a” to “point b” by avoiding traps. Hitting a trap will reset your progress right to the beginning. This punishment gives the game the “Super Meat Boy feel”. Reasons for losing are always clear to the player, and there is very little friction to restarting. The player jumps back into the action as soon as they are killed, making it extremely addictive to just keep trying to beat a level.

The meta (the progression systems outside of the core platformer gameplay) is a re-hash of Clash of Clans. They’ve managed to modify the standard Clash of Clans formula into something that works very well with the core platformer gameplay. Just like Clash of Clans, King of Thieves asks the players to manage two layers of gameplay: attacking and defence. On attack, the player plays platformer style levels to steal gold and gems (more on this later). On defense, the player must design a base that defends against other players’ attacks. Players sessions are focused on stealing as much loot from players around the world to upgrade their own abilities.

The Session Loop

To deconstruct, I’d like to focus on session design. To do this, we need to break down the game into its daily action loop: the repetitive actions the player takes to progress in the game. Let’s evaluate each step in regards to how it impacts the way the sessions feel.

Looking back at the post on Flexible Sessions, the key principle of designing sessions is about creating a diminishing curve of value for sessions per day and for session length. Just to reiterate: The first rule is that the first session of the day should feel more impactful than the 2nd, 3rd, or 4th time the player returns. By the 5th+ session, this should give minimal value to the player. The second rule is that session length should also have a diminishing curve of value. Eventually a player should naturally feel that returning at a later point in the day would be more beneficial. These two rules make up strong session design.

So how does King of Thieves execute this?


Step 1: Collect Base Rewards

Each day the player begins their session with collecting the rewards from their dungeon:

  • Collect gold from their stash. (Optional Short Timer)
    This is a bucket-filling mechanic. Allowing players to collect from the stash as many times as they wish throughout the day.
  • Collect gold from successful defences. (Short Timer)
    Making sure players feel good about their defences, players collect gold for every failed attempt by other players in their dungeon. While not a lot of gold, this certainly feels good when you’ve come back after a long absence
  • Collect generated gems (Long Timer)
    Gems generate on the map on a longer cycle (multiple hours). 

You can see here that these three reward cycles each have varied timer length, which allows for strong session design. Short timers to value coming back more per day, but longer timers to reward daily play. Using rewards of varying length, the player has a clear diminishing value for returning multiple times throughout the day.

Step 2: Loot Dungeons with Keys

After the player has collected all their rewards, they want to maximize their cash for their current session. There is always the threat that other players in the world will steal any resources they have when they leave the game.

Players can choose between the PvP (left) or the PvE (right)
Players can choose between the PvP (left) or the PvE (right)

 To do this, players loot other player’s dungeons (PvP levels) or designer-created levels in a map (PvE levels). Player-created levels hold high value gems. Whereas the PvE levels have higher gold rewards (sometimes), unlock new gem generating mines and new dungeons which the player can move to. This system works because both PvE and PvP benefit the player in different ways.

 King of Thieves innovates with their pacing mechanics. Instead of using energy or lives like in most games, they use “Keys”. Keys refill like in most games with time. The key difference is that the amount of energy (or keys) the player needs to spend to enter a level is randomized.

Players can choose a lock. Each attempt costs a key. Only one of them gains entry. Randomized Energy.
Players can choose a lock. Each attempt costs a key. Only one of them gains entry. Randomized Energy.

The player chooses locks on a screen with their keys. If they get the right key, they enter the level. If they choose the wrong one, they must spend another key. The game supplies the player with more than the usual amount of energy (10+). However, some levels can use 1 key to enter, others up to 15 keys to enter. Why would ZeptoLab design a system like this?

This system doesn’t please all player types. I’m convinced ZeptoLab benefits more from this system than the player experience. Not an easy choice I’m sure as a designer, but these sacrifices are sometimes necessary in a free to play game.

 From the onset, this system feels arbitrary, just like an energy system. The player’s ability to loot is capped by some tacked on economy. Compared to Clash of Clans, Clash’s pacing mechanics make sense: you will eventually run out of troops to loot opponents. King of Thieves just says you run out of “keys”. Could this be fixed if the player had to “craft” keys in their base? Could this be fixed if the player had to build clones of their shadow player to start looting? Maybe. Overall I’m not a fan of the system, but I understand the benefits for ZeptoLab.

 Because the system is randomized, players can try for one more level even if the player only has 1 or 2 more keys left. If they get lucky, this feels great. They get to play the level with little cost. If they fail, they are presented with this screen:


This screen is a high conversion screen for their video ads. Want to keep trying? Watch a video ad. Video ad revenue is becoming more and more interesting in the mobile free to play space, and I completely understand why ZeptoLab wanted to create a pinch point for this type of system. Players then binge watch some videos to get in that “just one more play” feeling.

On top of converting players with video ads, this type of randomized energy system also creates a nice way to balance harder and harder levels. Players can upgrade their key storage limit to be able to reach higher and higher levels. The higher the level, the more locks that the player must attempt. Also, this can create an interesting session per day value curve. ZeptoLab can use metrics like sessions per day and session length in their decision about how lucky the player is. This may be dubious, but this type of “invisible hand” to guide the session design can be very powerful.

In the end, I’m unsure if this system of randomized keys was the best choice for King of Thieves. The system is a unique design and I’m excited to see what the market thinks of it. Just based on the conversion to video ads, I think this could be something to try for other genres.

Step 3: Upgrade Your Base (or Else!) 

After the player has looted as many dungeons as they could in that session, they may use their found coins to upgrade their dungeon and resource generation. Any coins left over will most likely be stolen, so players attempt to spend every coin they looted. This promotes going for one more looting session, or extending the session to purchase more gold.


Step 4: Fuse Gems

 The key to the meta and progression of the game is fusing of gems. Players collect gems from mines on the world map and by looting other players in the world. The player then takes the gems collected and fuses them in their base.

 Fusing usually takes many hours (3+ hours for a usual gem). During this time the gems in this fusing ritual are open for stealing by other players. This is the most anxiety-inducing timer in the game. A gem will be stolen unless they keep the game open or have amazing defences. I spent about two hours on a weekend keeping the game open while watching movies because I was too afraid to close the app and lose my gems.

So why would players opt-in to this nerve wrecking timer?


Increasing gem value is the goal of King of Thieves. The total value of your gems is how you rank in the game. Players are looking to retain only the highest quality gems (which is shown by a number). However, there are only limited slots the player can have to hold onto gems. So players quickly run out of slots and are forced to fuse gems together to make more slots for higher level gems.

This was a very, very smart design choice by ZeptoLab. This creates a natural cap for progression and creates a lot of very interesting choices for the player. It also creates an obvious high conversion item for monetization: the extra slots for gems. Similar to the builder in Clash of Clans, ZeptoLab has created a high conversion item out of these extra slots. I’m convinced that if they brought this to the forefront and made it cheaper for first time players, this could be a strong conversion item.

Step 5: Optimize Defences

After they’ve completed this loop: collect, attack, upgrade, fuse… what’s left?

 Just like in Clash of Clans, players can extend their sessions by optimizing their dungeons defence layout and adjust the positions of traps. This comes with one caveat: the player must be able to beat their own level twice… in a row.


This definitely creates a session extension. I’ve spent well over a half an hour trying to create the optimal dungeon design. All this time was not incentivized by the game, but I wanted the best layout possible. This is exactly what you want to create in your session design. A session extender that players can take as little or as much time with as they wish. The value diminishes over time.

What they did right: Social Pressure Mechanics

ZeptoLab shows an excellent example of how to add effective social mechanics to a game. Asking players for help to retrieve lost gems creates social pressure. I feel good about helping my friends, I enjoy when my friends help me out when I’m less active. I rely on my friends to help me optimize my fusing timers. The value of having active friends is apparent.


 The league system creates a nice PvP environment with a clear reason to collect gems. Instead of feeling like I’m levelling up just based on some arbitrary number the designer has created for me (ex. collect 5000 gem value in 5 days), I’m competing against a living breathing opponent. I have to be engaged to compete, and the number is always growing so I never feel safe about my position. Sometimes I wish there were ways to specifically steal from other players on the leaderboard you were competing in. This would really drive up the competition.

King of Thieves also uses the same idea of clans in Clash of Clans. King of Thieves wants you to join a Guild. While the system is clearly in its infancy, it shows a commitment by ZeptoLab to the future of the game. Guilds are what will really drive the long term retention, and including it in the global launch was important. The mechanics at this point are still too early, but in the coming months I expect that ZeptoLab will build from this base and make very competitive play between Guilds stealing gems from each other. I hope they find a way that Guild members can work together on a dungeon or a raid. It would also be interesting to incentivize Guilds to put their most valuable gems in a vulnerable position. This will really drive competitive gameplay between the Guilds and give a collective goal.

What they could improve: Hardcore Skill

 In the translation of the Clash of Clans metagame to Super Meat Boy style mechanics, something fundamental was lost. Because platformer gameplay is inherently so skill-based, the translation still feels like a massive amount of skill is required to win.

 Clash of Clans (as discussed before) although it requires some mix of stats and skill, the main determinate to win each fight is Stats. If you have an amazing army, you are going to win. If you have spent a ton of time (or money), you will be able to dominate against an opponent lower than you. As you defeat more of these easier players, you will be matched higher and higher in the leaderboards. This will demand more skill, but mostly more stats. This system allows players to “hover” around matchmade opponents that challenge their skill level, but still require high stats. Even if I’m terrible at selecting where my troops go, I’m still progressing, and I may be lower on the leaderboard compared to other players at my stat-level, but I still am progressing.


King of Thieves is never flexible over the amount of skill it requires from players. As you progress in the game, it keeps demanding more and more skill from its player base. As a result, the game feels very hardcore. The players that reach the end game are a smaller and smaller niche of highly skilled players. Why does this happen?

As the game progresses, players slowly get harder and harder obstacles they can place in their dungeon. In order to set up a dungeon that is difficult, the player has to beat it themselves. As a result of this system, unless a player is highly skilled, their dungeon, regardless of the defences, will remain at the same low level of skill-difficulty. There is no way for a player to increase their defence without actually being far better at the platforming game.

There are some stats that affect the game: the damage of the obstacles, your shadow’s equipment and armour, the amount of keys you have, etc. But these stats clearly take less of a precedence over the skill. In my opinion, there are some levels that you just need high skill. So as you progress in the game, no matter how much time or money you’ve put into the game, you will reach levels that it doesn’t have an impact if you don’t have the skill. There is no “hovering” in the matchmaking that allows players to feel progress regardless of skill. Players with low skill will feel it: they are punished by losing levels very often.

This is most likely an artifact of trying to combine a high-skill genre (Super Meat Boy) with Clash of Clans. While this pushes away players that are expecting a lower skill level, I think it also engages the highly skilled players even more. The tradeoff between a highly engaged niche target audience and a flexible broad audience appeal is incredibly difficult to get right.

The Results:

On launch, the app was featured by Apple. This drove hundreds of thousands of downloads, but has yet to crack the Top 100 US Grossing. Can it get there? This will be a extremely tough. After a featuring, the only way to drive the necessary volume to reach the Top Grossing Chart is to purchase installs. This is extremely costly.

However, the game supports very strong early day retention and with more work can improve their long term retention. With continual improvements this game has a chance to reach a stable position in the Top 250 Grossing.

Personally, I’m cheering for ZeptoLab. This design is refreshing. I had the feeling that the mobile free to play space is even more risk-averse than the console/pc space. This feels like a step in the right direction. This is a game ZeptoLab should be proud to have worked on. I hope other game developers can look at this example on how to innovate in new genres