Open source flight simulator under GPL licence for Windows, Linux, Mac OS-X, FreeBSD, SUN/Solaris, and SGI/IRIX platforms.

Free OpenGL billiard game for linux. Includes description, FAQ and downloads

Describes space simulation in which players trade and bounty hunt. Includes features, forum, manual, and downloads of beta versions

Multi-platform Open Source port of the classic sci-fi game Star Control II, based on the original source code of the 3DO version, with new features including network play and remixed music.

Microsoft's own Open Source Initiative, using the GPL'ed Marathon 2 source code, called Aleph One.

An Open Source project in which the user takes the form of Tux (the Linux Mascot) and races downhill through alpine trails.

A Doom engine that closely emulates the original game.

Small driving simulator/demo with open source code

Port of ID Software's classic Doom game with OpenGL

An open source 3D chess interface. It uses OpenGL and GtkGLArea (from GTK+) for UNIX platform.