31 December 2013

Clash of Clans - match-making and retention


A player can only be attacked when she is offline. Hardcore trophy hunters are online most of the time, because trophies are mostly gained in offense, not in defense (some gemmers even ignore upgrading their buildings). Thus it can take a while for high trophy players to be given a match when they are attacking. Players complained about the player base being too small to support trophy hunters, when the game came out in August 2012. Trophy hunters kept complaining, and the most SC did was force players to logout at least every 8 hours.

The fact that players can only be attacked when offline has another consequence. When a player logs in while under attack, she does not see what is going on. Instead, she is given a loading screen for up to three minutes. This is inelegant, and it could be improved.

As others have noted, in Clash of Clans, the clans don't really clash. Players of the same clan can not gang up against a rival clan. The only thing they can do is chat together and donate troops to each other. Some even say that the game only provides the illusion of a multiplayer game. Players can not even choose who they will attack. The system gives them villages from other players one at a time, and the player has to next sometimes for 10 minutes to find an appropriate target.

Match-making is also SC's way to remove churners from the game. Churners are called inactives in the community. Inactive bases have full mines, so they provide a lot of loot for little effort. To keep the loot in check, SC removes inactives from the match-making queue every few weeks. Players notice it very quickly: one day, they loot 300k gold per raid on average after 30 seconds of nexting. The next day, it takes 10 minutes of nexting for a 150k-gold raid. I think a lot of players stop playing when they suddenly can't find loot.

Retention and monetization

Achievements such as unlocking the Dragon, reaching a certain amount of trophies, or looting 100M gold, all reward the player with gems. These gems are the only way to acquire builders to speed up the upgrading of buildings. Thus for players who do not spend real money to buy their builders, these achievements are long-term goals. For many players, the game is about the journey, not the end. Achievements also work in the beginning as quests guiding the player through the basic game mechanics.

30 December 2013

Clash of Clans - polish

SC spent a lot of time polishing CoC. They launched the game in beta only in Canada for exactly one month. I have never heard of such process for other iOS games. As a result, the game has been praised as well-presented and easy to play, with a smooth, clear interface and animations that are packed with character.

The depth of CoC's mechanics is a much-argued topic. When the game came out in mid 2012, a reviewer argued that the actual strategic elements of gameplay are far too lightweight and hands-off to satisfy fans of more traditional strategy games. But another praised CoC's unbelievably high replay value thanks to its varied troops, and distinctive performances of all defensive buildings, walls and traps that generates infinite possibilities for battles. The core of the argument comes from the fact that once a troop is deployed, the player is not in control of it anymore: the unit just behaves according to its AI behavior until it dies or the battle times out (after 3 minutes). In the first few weeks of play, CoC battles feel not precise and even frustrating. But then some players realize that battles are simply about unleashing a horde of troops to overwhelm the enemy. Some even go so far as saying that even a moron with no strategy at all will advance in the game with time. It is true: in the first month, the mechanics are so forgiving that some adults even let their infant playing CoC for fun.

But after a few months of play, I realized that no two units or buildings have the same function or effectiveness in battle. For example, among meat shield units, Barbarians are the cheapest and fastest to train, Giants also fast to train but more costly, and Golems the slowest and most expensive. But these units are actually very different in practice: Barbarians target any building, whereas Giants and Golems only defensive buildings. Giants have five times more DPS per housing space than Golems, and therefore can pierce through walls, whereas Golems need wall breakers to open the path. Even though the most powerful units are usually the most expensive and slowest to train, the behavior of the units in battle allow for dozens of attack strategies. So the game is essentially deceivingly simple, and its complexity grows with time. In my opinion it's great for newcomers and loyal players alike.

A lot of tiny details contribute to the great play experience. For example, the Dragon generates a lot of excitement when it becomes available at TH7. Players can donate troops to each other through their Clan Castle. Dragons can only fit in a Clan Castle level 3 or above. The Clan Castle reaches level 3 at TH6. So if I am TH6, even though I can not produce dragons, I get the thrill of using one through my TH7 friends.

The game also receives patches with new content, bug fixes, and balance tweaks roughly every 50 days. An observer suggested in September 2012 that SC implements super units, in which players emotionally invest to, because these units sell like pop corn in a movie theater. Heroes got introduced in January 2013. Unlike other units, which disappear after being used in battle, heroes stay after a battle and only need to be recharged after a battle. Heroes also provided a sink for dark elixir, a game currency introduced in the same patch.

In my experience, players were not very emotionally invested in their heroes. Getting a permanent hero for the first time generates the same craze as training a new disposable troop such as the dragon. The craze fades off quickly, and heroes are just a way to loot more gold. This lack of emotional attachment may be due to heroes being human-looking. If they were pets with accessories, players may be more emotionally invested.

While the base game was very polished when it hit the app store, each patch released so far has contained a couple bugs. Many of these bugs are graphical and directly observable when launching the game. Clearly, the QA for patches could be more thorough. Moreover, the aesthetic choices for buildings follow too many different styles: lava, electric, diamond, and so on. Players have complained about villages becoming ugly.

29 December 2013

Clash of Clans - mechanics

Clash of Clans (CoC) is a mobile game for Android and iOS. It launched in August 2012, was the most lucrative iOS game of 2013. CoC was developed by SuperCell (SC), a Finnish game company founded in 2010. In April 2013, SC was generating 2.4 million dollars per day with only two games: CoC and Hay Day, a Farmville clone. In October 2013, a giant Japanese conglomerate bought half of SC's shares for 1.5 billion dollars.

I have played CoC actively from February to December 2013. I always played the game for free.


At the first glance, CoC is very much like Farmville: two resources, namely gold and elixir, are produced automatically over time. But resource production is perfectly done compared to Farmville: crops do not wither if they are not harvested on time. So it's always rewarding to come back and collect resources from the gold mines and collectors (mines, for short).

Building upgrades

Most buildings can be upgraded by spending one of the two resources. Gold is used to upgrade defensive buildings such as cannons or walls. Elixir is used to produce troops to attack other players, and to upgrade troop-related buildings such as barracks or army camps. Mines can also be upgraded to produce more resources per hour, but also to store more resources until they are collected. For example, a level-2 mine takes 2h30 to fill up, which may encourage new players to visit the game more often. But players quickly realize that they are wasting resources during the night or a day at school. So players want to upgrade their mines to level 5 because then they take 10 hours to fill up. But upgrading a mine to level 5 requires Town Hall level 3, which itself requires a significant amount of gold, usually obtained after several hours of play. And that is how players get hooked.

Player versus player

After 3-4 days, the core mechanics change progressively. The amount of resources produced by mines becomes negligible compared to the cost of building upgrades. The player realizes that to keep her upgrades going, she must steal resources from other players, or from the solo campaign missions. The solo missions can only be completed once, so PvP is unavoidable. At this point, I suspect most players to take a decision. Some decide PvP is not for them, so they stop playing. Of those who continue, a very small minority decide that the game is all about competing against other players. These players are called trophy hunters, since winning a battle rewards the player with trophies. A leader-board shows the 100 players with most trophies. Most trophy hunters spend real money to instantly max their buildings and troops. They eventually become regular buyers, the 2% whales spending $200 per week.


The remaining 98% who decide to keep playing focus on stealing resources from other players. The most dedicated of them are called farmers; they train cheap armies and ignore trophies as long as they loot resources. Farmers are very practical and calculating: should they build an army costing 5-50k elixir in 15 minutes, and loot 100k-500k of resources from another player, or wait for their mines to produce 5k of each resource in these 15 minutes? Their behavior is obvious: 1) turtling is a waste of time, 2) they login when their army is trained, and 3) they logout when they have attacked and do something else (like playing another game) while their troops are training.


There are one elixir sink and two gold sinks. Elixir is sunk when the player trains expensive and powerful troops. Since farmers usually train fast and cheap troops, they often have more elixir than they can spend. The first gold sink is walls. Each of the 250 walls costs 8M gold to max out. The best farmers make 1M per hour, so we're talking about 2,000 hours of (sporadic) gameplay here. For someone playing 5 hours per weekday night and 20 hours during the weekend, walls take around 10 months. So walls are a humongous gold sink. The second gold sink lies in the match-making. When a player goes to attack, she is presented with another player's village. If there is too little loot, she can next for 200-1000 coins. Spending 50k gold in nexts to find a 200k-gold raid is very common. That second sink is very big too.

Pace of progression

To give an idea of the pace of progression, below are screenshots from my village from March to November 2013.