Many sites, like Inside Social Games, rank the top games on Facebook based on the monthly active users, but daily active users is a much more instructive measurement if you want to understand how engaged users are with a specific Facebook application. For example, using data provided by Developer Analytics, Mind Jolt is the #2 game application when looking at Monthly Active Users (over 16.3 million) but the daily active users is just under 2.1 million, ranking it 10th overall.

By comparing the Monthly Active Users (showing the reach of a game) versus the Daily Active Users (showing the engagement), you can see which games are the stickiest and which ones have a real churn issue. For Mind Jolt in the example above, they have a 12.6% stickiness factor (2.1/16.3) meaning of the 16.3 million people who used the application, only about 13% use the application daily.

The average “Sticky Factor” for the top 25 applications on Facebook is 18%.

The Big Churners

So what applications attract users but can’t seem to retain them? Many of these are the past stars of Facebook, initially popular like Living Social (the Top Five lists) or Movies (quiz mania). A passing fad with little staying power:

Application	Monthly Active	Daily Active	Sticky Factor
Movies	20,446,560	894,197	4.4%
Causes	23,401,221	1,067,921	4.6%
We’re Related	17,007,440	777,749	4.6%
Top Friends	12,383,916	580,073	4.7%
Living Social	23,013,301	1,763,091	7.7%

The Most Sticky

There is no surprise that some of the most useful applications (Facebook for Blackberry and Mobile is just outside the top five) are among the most sticky, but the top games (Farm Town and Farmville) also rank highly, suggesting good game play design is bring users back every day. Here’s the top five:

Application	Monthly Active	Daily Active	Sticky Factor
Facebook for Blackberry	7,746,122	4,284,788	55.3%
Happy Farm	1,682,541	674,263	40.1%
Farm Town	14,902,946	5,159,788	34.6%
Farmville	17,036,997	5,322,426	31.2%
Restaurant City	8,733,452	2,605,067	29.8%

How are the Top Developers Doing?

Of the top multi-game providers Zynga and Playfish are way ahead the rest and have some winners and under-performers:

• Zynga (16.3 mllion daily active users): Farmville 31.2%, Mafia Wars 25.4%, Vampire Wars 24.9%, YoVille 20.3%, Texas Hold’em 19.4%, Street Racing 16.4%
• Playfish (8.0 million DAU): Crazy Planet 33.6%, Restaurant City 29.8%, Pet Society 26.1%, Word Challenge 8.6%, Biggest Brain 7.4%, Geo Challenge 7.2%,

Other key developers:

• PopCap (1.3 million DAU) is the “grand-daddy” in the casual games space and their initial foray into Facebook with Bejeweled Blitz (a slightly above-average 21.6% stickiness rate) is just outside the Top Ten applications. Zuma is up next for them.
• Metrogames (1.2 million DAU) has tried to bring arcade games in with middling success, in large part due to poor stickiness: Biotrnic 12.2%,, Waka-Waka 9.6%, Typing Maniac 5.9%
• Playdom (0.9 million DAU), which is looking to repeat its success on MySpace to the Facebook platform is generally launching games with lower than average stickiness: Sorority Life 14.1%, Mobsters 11.7%, Poker Palace 11.2%

By using this simple factor, you can now benchmark your application versus others and work to optimize your retention. When it comes to social games, it may just come down to how fun the game is.