The original list became intractable so, by popular demand, I reorganized the list by genre and thinned it down to (in my opinion) the most popular and polished games. I've steered clear of including demo games, games in development with limited playability, and games of questionable legality.
First Person Shooter (FPS)
Action
Real Time Strategy (RTS)
Turn Based Strategy (TBS)
Arcade
Moved back to PC Games. Restickied.
-Schadenfroh (AT Mod)
First Person Shooter (FPS)
- Wolfenstein: Enemy Territory (Windows, Mac, Linux | Multiplayer | Wikipedia) - Expansion to the commercial World War II FPS Return to Castle Wolfenstein.
- America's Army (Windows | Multiplayer | Wikipedia) - Modern realistic US army tactical FPS.
- F.E.A.R. Combat (Windows | Multiplayer | Wikipedia) - Multiplayer component of the commercial horror FPS F.E.A.R.
- Starsiege Tribes (Windows | Single Player, Multiplayer | Wikipedia) - Commercial sci-fi FPS.
- BZFlag (Windows, Mac, Linux | Multiplayer | Wikipedia) - Tank battle FPS.
- Wulfram (Windows | Multiplayer | Wikipedia) - Vehicle battle FPS with RTS elements.
Action
- Grand Theft Auto 1&2 (Windows | Single Player, Multiplayer | Wikipedia) - Commercial criminal shooter.
- Soldat (Windows | Single Player, Multiplayer | Wikipedia) - Run and gun similar to Worms with FPS elements.
- Little Fighter 2 (Windows | Single Player, Multiplayer | Wikipedia) - Anime scrolling fighting game.
- Allegiance (Windows | Multiplayer | Wikipedia) - Commercial space combat shooter with RPG elements.
- Freespace 2 (Windows, Mac, Linux | Single Player, Multiplayer | Wikipedia) - Commercial space combat shooter with RPG elements.
Real Time Strategy (RTS)
- Savage: The Battle for Newerth (Windows, Mac, Linux | Single Player, Multiplayer | Wikipedia) - Commercial sci-fi 3D RTS and FPS.
- S.W.I.N.E. (Windows | Single Player, Multiplayer | Wikipedia) - 3D RTS with animal armies.
- Spring (Windows, Linux | Multiplayer | Wikipedia) - 3D clone of commercial Total Annihilation.
- Ground Control (Windows | Single Player, Multiplayer | Wikipedia) - Commercial 3D RTS.
Turn Based Strategy (TBS)
- Freeciv (Windows, Mac, Linux | Single Player, Multiplayer | Wikipedia) - Clone of commercial Civilization series.
- Battle for Wesnoth (Windows, Mac, Linux | Single Player | Wikipedia) - Fantasy themed adventure.
- GunBound (Windows | Multiplayer | Wikipedia) - Turn based anime artillery game similar to Worms.
- MegaMek (Windows, Mac, Linux | Single Player, Multiplayer | Wikipedia) - Clone of Classic BattleTech board game.
- Scorched 3D (Windows, Mac, Linux | Single Player, Multiplayer | Wikipedia) - 3D clone of Scorched Earth.
Arcade
- StepMania (Windows, Mac, Linux | Single Player, Multiplayer | Wikipedia) - Clone of commercial Dance Dance Revolution.
- Neverball (Windows, Mac, Linux | Single Player | Wikipedia) - Clone of commercial Super Monkey Ball.
- Tux Racer (Windows, Mac, Linux | Single Player | Wikipedia) - Penguin racing simulation.
- SuperTux (Windows, Mac, Linux | Single Player | Wikipedia) - Clone of commercial Super Mario.
Moved back to PC Games. Restickied.
-Schadenfroh (AT Mod)