Aleph One is a 3D first-person shooter game based on the game Marathon 2 by Bungie Software. It is set in a Sci-Fi universe dominated by deviant computer AIs and features a well thought-out plot. Aleph One was originally a MacOS game, but a cross-platform version ("Aleph One/SDL") based on the Simple DirectMedia Layer (SDL) library is currently under development which runs under Unix, BeOS, and Windows.
Circus Linux! is a clone of the Atari 2600 game "Circus Atari." The object is to move a teeter-totter back and forth across the screen to bounce clowns up into the air. When they reach the top, they pop rows of balloons and then fall back down. If you don't catch one, you lose a clown.
Dreams Eternal is an FPS game that focuses on a strong story line and puzzle solving. It is set in the dream world. The very short summary of the story is that a scientific experiment went wrong and everybody is stuck in the dream world. You have to end this experiment by hopping from dream to dream. In every dream you have to find clues to try to find out how the experiment can be aborted.
Freeciv is a multiuser reimplementation for Unix/X of the famous Microprose game of Civilization. By default, the game is an improved Civ II, but this can be customized; modpacks for near-100% compatibility with Civ I and Civ II are included. Multiuser gameplay is real-time: in each turn, all human players move concurrently. The game is designed to remain fairly playable even on poor network connections. Freeciv can also be played on standalone machines, and its AI players are a good challenge for beginners. The source code comes with the server, two X clients, and non-X clients for MS Windows and Amiga. Freeciv is released under the GNU General Public License. It is maintained by an international team of coders and enthusiasts, and is easily one of the most fun and addictive network games out there.