BZFlag is a 3D, multiplayer, tank battle zone, capture the flag game that pits players against each other in a networked environment. It runs on Windows 95/98/NT/2000, Linux, MacOS 10.x, Irix, Solaris, and others. An OpenGL accelerator is highly recommended, but it is playable with 3D in software.
pydance is a dancing game written in Python, formerly named pyDDR. The idea is simple. There's a floor mat with arrows, and the game scrolls arrows up the screen to the beat while playing a song. When the arrows reach the top of the screen (not sooner and not later), the player hits the corresponding arrow on the pad, and given that it's hit on time with the beat, points are scored. Based on how well the dance is put together, s/he is graded at the end of the song. Both keyboard and mat play are supported.
"The Game" is a project designed to simplify the process of producing any high-quality cross-platform 2D or 3D graphical computer game. The hope is that any game can be produced simply by changing a few settings and pressing a "compile" button. The project has three "deliverables": a game engine library to abstract across the set of all possible computer games (applying object-oriented design methods to the general problem in such a way as to be usable in specific instances); a graphical interface for easy game design (an exercise in human interface design); and a gaming package with a lot of shiny games to play.