(Mashable) -- Facebook game developer Zynga has proved once again that it knows exactly what it needs to do to keep millions of Facebook users happy and occupied.
In less than a month, its latest game "CityVille" has become the most popular application on Facebook, surpassing Zynga's previous hit "FarmVille" in all areas.
According to AppData, "CityVille" now has 16.8 million daily active users, compared to "FarmVille's" 16.4 million. Looking at monthly active users, "CityVille" is also ahead with 61.7 million users, while "FarmVille" trails behind with 56.8 million users.
Zynga's "FrontierVille" and "Texas HoldEm Poker" also round out the top five: put those four apps together (we'll disregard the fact that many of those users overlap for a second) and you have a very impressive number: 184 million active users across four games.
The only non-Zynga app in the top five list is "Phrases," which at one point threatened to take the top place, but is now overshadowed by both "CityVille" and "FarmVille."
"CityVille's" future success wasn't hard to predict after an amazingly good start at the beginning of December, but it's still impressive to see Zynga amassing tens of millions of users in a matter of days, proving that all that venture capital that went into the company isn't there by accident.
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