Cube Runner is a very simple time-based 3-D flight game that was birthed in early jail-broken iPhone days. It started free, and remains a free game on the iTunes Application Store.
This is probably one of the most simple pickup-and-play games on any platform. The player is a "ship" (the triangle at the bottom of the screen) that is constantly flying forward through an ocean of 3-D boxes. If a box is hit, the game is over. The score gradually goes up the longer you survive. The ship is controlled by tilting the iPhone to the left or to the right, much like a steering wheel.
Cube Runner contains three levels of difficulty, with progressively harder levels the longer the player can stay in the game. At a certain score point, levels can
change color (the first level design change has been dubbed "the Matrix level" for obvious reasons). As an added bonus, fans can create their own levels using the developers simple-yet-effective level builder located at http://andyqua.co.uk/CubeRunner/Level_Design.html. The user is responsible to upload the levels using their own webhost. The levels can be downloaded and played in-game by entering the direct link to the zipped level pack.