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CityVille Explained, Part 1
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CityVille Explained, Part 1

December 28, 2010 Article Start Previous Page 3 of 4 Next

Now let’s talk about how CityVille keeps users engaged.

Most social games are considered amusements for the majority of players, so successful social game developers focus on delivering that kind of engagement. They are obsessed with retention, a commonly-used term to describe whether players return to a game or bounce from it, and the period of weeks or months that the average retained customer spends in the game before boredom finally sets in. Understanding retention is essential to achieving sustainable growth and revenue in a social game like CityVille.

But what are the levers of retention?

DAU over MAU

In order to understand what's really going on with a game, you need to look at the daily active users (DAU) as well as the monthly active users (MAU).

Tracking services like Appdata provide useful summaries of these statistics, as well as a calculation of one over the other. I find that the resulting percentage of DAU/MAU is the best underlying number to really know what's going on with a game.

Whether big or small, the DAU/MAU percentage tells me whether users are playing a social game as a distraction or an amusement (or even a connection, though that's pretty rare), and so gives me an inkling as to the application's true long term potential.

The percentage for CityVille started off extremely high. That's not unusual in the first week of a game's launch however, because everything is new, users are only discovering it for the first time, and the MAU figure has not had a full month to build up. A more stable example is FarmVille:

FarmVille has long been a standard-bearer for engagement on big games. These days it hovers around the 30% mark, which is fantastic, whereas many successful games exist around 20%, and some others drift down toward the 10-12%. Social applications that share quizzes and the like commonly only achieve 3-5%.

Zynga maintains one of the highest overall rates among the big developers at approximately 23%. Crowdstar has only 11%. Playfish/EA has 18%. Six Waves has 8% for its own games and 18% for games it publishes. Disney Playdom has 11%. Digital Chocolate has 16%. RockYou has 8%. Wooga has 18%.

You get the picture. Why this is so has three reasons:

1. Quizzes: The reason why Crowdstar in particular has a low percentage is because one of their most popular apps is a quiz engine. The quiz marketing tactic is a perfectly valid one, and it tends to award high MAU numbers, but low DAU. This often gives a skewed impression of how important a company might actually be in the social game space. Zynga has no quiz engine (that I’m aware of).

2. Visibility Strategy: This is a bit of a repeat from the first part of the article, but the prevalence of publishing options in particular creates more hooks for lapsed players to return to a game. The Facebook economy works geometrically and exponentially, and that applies to retention as well as initial interest.

3. Game Activity: How Zynga structures its games, particularly with respect to time- and click-based dynamics, encourages players to remember to come back and play some more. That's what I'm going to talk about mostly in this article.


Late last year, Playfish released two games that they probably shouldn't have. One was Poker Rivals and the other was Gangster City. Each was, in its own way, a better execution of the incumbents in their genre, Zynga's Texas Hold'Em and Mafia Wars, and yet each has proved to be a failure.

The lesson is not that you can't fight Zynga.

Crowdstar faced off a challenge from Zynga trying to eat its Happy Aquarium market with FishVille, and while both are well past their heyday, FishVille proved to be the loser. Similarly, PetVille tried to take on Playfish's Pet Society, but now has no more than 60% of Pet Society's users.

The lesson is that context matters.

A hidden, but determining, factor for retention is whether this is the first time that players have encountered that game type. As most Facebook games fall into the category of amusements on the Engagement Hierarchy, players don’t distinguish them. It's therefore important to be the first one of that type that the average user sees.

Interestingly, this may have significant consequences for CityVille. After all, social city-building games have now been around for a while, and although CityVille is doing some things differently, the game may end up falling into the same trap as FishVille or Gangster City. It's far too early to tell.

So let’s get on to talking about the game activity.

Click Click!

The core game dynamic of CityVille is click-to-do. Click to build, click to collect, click to plant, click to harvest, click to deliver supplies. It’s reminiscent of the PC game Black and White in that although you are ostensibly the manager of the city, you actually do a lot of manual labour.

So much clicking is oddly compelling. The player doesn’t actually have to click to do everything (collected items will self-collect if left on the ground for example) but there’s a nice feeling that comes from such activity. It’s interactive, and that in turn makes the game mildly immersive by making the player feel like they are doing something, even if that something is essentially just sweeping up.

Click activity on this scale also has a downside, which is that it doesn’t scale well. My current city in CityVille is only a couple of streets in size, but when I do expand it out significantly, I think I might find the extent of such manual maintenance becomes boring.

Dual Timers

Timers prevent endless clicking. As I described in the previous post, social games like CityVille employ two kinds of timer: Specific timers on buildings or crops, and general timers in the form of energy.

Timers are deliberately staggered. Planting strawberries takes 5 minutes for them to grow, a cottage generates coins once per hour, and corn takes 24 hours to grow. So you can see why these activities encourage repeated visits. With FarmVille (which uses the same system) there are many apocryphal stories of players getting up in the middle of the night to harvest their virtual beetroot. In fact this sort of timed game dynamic goes at least as far back as the Excel-in-space game Planetarion.

Energy works another way. It is a limit on the amount of click actions that you can take in a short space of time. Some clicks, but not all, dock the player a point of energy. Collection docks energy, for example, but supplying doesn’t. Constructing a building docks energy, but clearing dead crops is free. Energy is resupplied on its own timer at a rate of one point every five minutes, or replenished if the player attains a level.

Timers used in this dual fashion are incredibly effective. What they do is to deliberately set up a conflict whereby players have to wait to do everything they want, but in the mean time can do some of the things that they want. Rather than use one global timer, as Planetarion did, the use of multiple timers creates the sensation that there is always something to do while waiting.

The mix of the two is highly compelling. While players enjoy the click activity (see above), timers essentially introduce delayed gratification, and then CityVille offers premium ways to circumvent some (but not all) of that delay. One of the foundations of monetisation in CityVille is buying more energy, for example. This gets you more activity and more clicks.

(I'll talk more about money in the last part of this article).

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Samuel Green
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I find it interesting that this article, while mostly comprehensive, misses out on 2 of the most engaging features in CityVille.

"All of the people wandering around, as well as the plants and trees are purely decorative."

This is incorrect. CityVille uses the same feature as the highly successful Millionaire City, whereby decorations boost the income generation of nearby houses/businesses. It's a very compelling feature, which is simple, but tactical. An example of a slightly more complex game mechanic which appeals to those who seek more advanced gameplay, but doesn't scare off or confuse casual players.

There is also the 'click combo meter', which is my favourite innovation of CityVille. Zynga have made clicking a lot more fun, by giving you a combo meter to try and maximise. As you collect rewards, it counts what you're gathering and the more you collect, the bigger the bonus you receive. Due to the time it takes for buildings to collect (you can do one at a time, and it has a small progress bar), you have to time and plan your clicks, and energy, to maximise the meter. You can't click everything at once, because it starts to auto-collect (which doesn't add to the meter), but you have to click regularly to try and avoid the 4-second 'combo breaker'. Like the decoration income bonus, it's a mechanic which is highly compelling for those who are disillusioned with boring city games, but it's ignorable by those who are happy with the bread and butter.

I think these features are fascinating and, when I get some free time after the holidays, I'm planning to have a CityVille 'race'. I will have 2 accounts, running simultaneously, and will see if playing 'hardcore' (using the decorations tactically, and the combo meter) is rewarding enough to make it worth it vs casual 'mindless' play.

This is why I was a bit disappointed with this article, it seems to explain the very obvious, but doesn't really look at the increased depth that Zynga have added to their game. I am not a fan of Zynga games, or how they achieved their success, but CityVille has actually impressed me.

Henric Suuronen
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I enjoyed this article a lot, very good observations - thanks for writing it!

I do agree with Samuel that the boosts decorations give are very important as they add tactical and optimization gameplay - smth new casual players don't have to mind but when they become more experienced they start to love in the game.

Another comment of mine on:

"Gating used to be a policy violation in Facebook games because the games used them as compulsory viral mechanisms"

The work around on this is to offer users the possibility to buy (with real cash) the gated content which turns the gated content to resemble any premium (hard currency) content inside the game.

Thanks again for the good article!