Less than a month after its launch, Zynga's CityVille has become the world's most popular game. According to AppData, CityVille just reached 61.7 million monthly active users, and with that, the game nabs the number one spot from Zynga's other social gaming phenom, FarmVille.
This gives Zynga a total of 261 million monthly active users - clearly nothing to scoff at. However, despite dominating social gaming this year, the challenge for Zynga has been to continue to build on the massive success of Farmville and to show that the game wasn't simply a one-hit wonder.