Angry Birds has finally arrived on Facebook after more than a year of development. The release makes good on the promise Rovio’s “Mighty Eagle” Peter Vesterbacka and Rovio Asia SVP Henri Holm made last month when they announced the Facebook version of the game would launch on Valentine’s Day.

The Facebook version of Angry Birds is different from the Chrome, Google+ and mobile versions of the game in several ways. There are four new powerups to buy in addition to the Mighty Eagle, but unlike the mobile version, where a single lifetime purchase of $0.99 unlocks the powerup, players of the Facebook version can only purchase limited number of powerups that range from 20 uses for $1 to 1000 uses for $20. The Facebook version of the game also includes 15 exclusive levels and a new item called Total Destruction Feathers, which are earned by using the Mighty Eagle. Rovio has also expanded the game’s social features for Facebook, integrating Open Graph so users can add the app to Timeline, creating a more visible leaderboard that stays on the right side of the screen and allowing players to send and receive gifts. Players can also collect bonuses for playing every day. The game also has some sort of avatar functionality which is still labeled as “coming soon.”

Rovio first announced it would bring the game to Facebook last March, but the game’s launch was delayed several times. Angry Birds made its web debut as a Chrome app in May 2011, and was a Google+ Games launch title.