Games

OpenArena - OpenArena is an open-source content package for Quake III Arena licensed under the GPL, effectively creating a free stand-alone game. You do not need Quake III Arena to play this game. Operating system: Windows, Linux/Unix, OS X
Scorched 3D - Scorched 3D is a game based loosely (or actually quite heavily now) on the classic DOS game Scorched Earth "The Mother Of All Games". Scorched 3D adds amongst other new features a 3D island environment and LAN and internet play. Scorched 3D is totally free and is available for both Microsoft Windows and Unix (Linux, FreeBSD, Mac OS X, Solaris etc.) operating systems.
ScummVM - allows you to port many classic point-and-click adventure games to nearly any platform you like. Supported games include Simon the Sorcerer 1 and 2, Flight of the Amazon Queen, Beneath A Steel Sky, Day of the Tentacle, Broken Sword 1 and Broken Sword 2, Monkey Island, Sam and Max, and dozens of others. Operating system: OS Portable.
StepMania - can be played using the keyboard or a sensor-laden “dance pad”. StepMania has game modes similar to Konami’s Dance Dance Revolution and Andamiro’s Pump It Up, Amuseworld’sEZ2Dancer, and Konami’s Para Para Paradise. Operating system: Windows, Linux/Unix, OS X, Xbox.