Great news for people who love birds and hate pigs: this week Rovio, developer of some of the top iPhone games, announced that it's bringing its marquee title "Angry Birds" to Facebook, adding in new features to make the game social-network-friendly. Rovio's top bird, Peter Vesterbacka, told The Next Web that the release was targeted for May, and that the Facebook version would have a more "collaborative nature" and give a larger role to the villains of the iPhone game, the pigs. "Angry Birds has taken the world of iPhone gaming, and indeed mobile gaming, by storm -- Rovio reported last month that 200 million minutes of the game are played every day, and the game generates $1 million per month in ad revenue. As a gaming enthusiast, I have high hopes for Rovio's entry into the world of social gaming on Facebook. Currently, the top games on the platform belong to Zynga -- #1 and #2 are "Cityville" and "Farmville," respectively. As revenue generators for Zynga, they're doing quite well, but as games, they leave much to be desired. The core of their gameplay mechanic is the grind, which I've written about before -- the repetitive behavior/reward cycle that keeps people playing, but not fully engaged with a gaming experience. Other gaming pundits have gone so far as to argue that social games, as they currently operate, are evil. The primary determinant of a game's success on Facebook right now is not necessarily how good the gameplay is, but how effective the game is at making you share it with your friends -- and Zynga's games have mastered this model. But it's clear that this model isn't sustainable. Take a look at "Farmville"'s monthly active user and daily active user stats over the last month. and you can see a steady decline as users get tired of the grind and quit. What Rovio could bring to the Facebook platform is true competition for better gameplay, not better sharing mechanics. No doubt Rovio's developers are taking a lesson from Zynga's when it comes to how to get people to involve their friends. But hopefully all Facebook game developers will take clues from Rovio, and other highly successful app developers, when it comes to gameplay.