Every other week, Gamasutra examines the most popular Facebook games according to monthly active users, looking at the top titles and developers on the social network to see who's attracting or losing players. Three weeks after its launch, Zynga's restaurant sim ChefVille is already the ninth most popular game on Facebook, ahead of FarmVille -- the developer's new releases tend to grow their audiences extremely fast, thanks to its huge cross-promotional network. ChefVille now has 15.7 million players, almost all of whom began playing in the last week. The game's thriving audience helps pad Zynga's total userbase, as its other major titles are losing players (it's unclear if many of them are just migrating to ChefVille). The Ville, for example, which is the most popular app on Facebook and has seen its numbers rise week-after-week for some time now, actually lost users in the last seven days -- coming down from 60.6 million to now 50.9 million. Texas HoldEm Poker has also lost 1.6 million users during the same amount of time, while Bubble Safari shed 200,000 players and Zynga Slingo shrunk by 1.1 million players. CastleVille has remained stable at 15.5 million users. Outside of Zynga's titles, other developers' games are starting to creep up Facebook's games leaderboard, including Wooga's Diamond Dash, FreshPlanet's SongPop, and Social Point's Dragon City. You can see the full list of the top 20 Facebook games along with exact monthly active user counts below:

Facebook Games Leaderboard

All charts and data are courtesy of Facebook application metrics and trends site AppData.