For those who have no idea what Blockout is: Blockout is the real 3D Tetris. You are given 3dimensional tetris pieces and have to stack them in a 3d pit. You need to form complete layers instead of just lines as in normal tetris.

BlockOut® II is a free OpenGL+SDL resurrection of the original BlockOut ® DOS game released by California Dreams in 1989. BlockOut® II has the same features than the original game with some graphical improvements. BlockOut® II has been designed by an addicted player for addicted players. An outstanding Feature is the online Highscore System including Replays for every submitted highscore.
BlockOut® II is an open source project, you can thus compile your own version for every imaginable system, for example MacOS, QNX and Solaris.

License: free