Each of the 105 levels has its own unique structure that you must blast through in order to get to the Green Pigs. There are several different kinds of birds that become unlocked as you play through the game. Some just fly though the air and crash, some become a bomb and some even multiply with the tap of a finger. This game offers a lot of fun gameplay for its low asking price of $0.99 and has great pick up and playability and high replay value. This game does a great job of challenging your logic and skill to beat each level.