Snap! is modeled after an old wooden board game I used to play. Pieces are placed on the board and a bar compresses them downwards. Players take turns removing pieces one at a time, if they cause the bar to move too far then the player loses points.
The Snap! source code is available under the MIT License. The purpose is to show how simple ChipmunkPro makes using the Chipmunk physics library from Objective-C projects. Snap is also available from the App Store for $.99.