All these titles are free software that are under the GNU General Public License, or some similar license. Because the source code is available and modifications can be freely (re)distributed, most titles will run on many platforms.

• Arianne is an open source MMORPG in development
• Armagetron is a multiplayer, 3D Tron lightcycles racing game
• Avanor is an open source roguelike game.
• Angband (another popular RPG in the roguelike family), and its many variants. The most comprehensive resource for Angband is at http://thangorodrim.net.
• Beneath a Steel Sky by Revolution Software which can be downloaded at http://www.scummvm.org/downloads.php.
• ClanBomber is a free DynaBlaster clone at http://clanbomber.sourceforge.net/
• Crossfire is an open source MMORPG
• Cuyo is a free Puyo Puyo clone at http://www.karimmi.de/cuyo/ (german)
• Daimonin is an Isometric MMORPG based on Crossfire in its first Beta
• Devet is a multiplatform strategy/puzzle game at http://devet.tuzsuzov.com/
• Enigma, an Oxyd clone with an unusual premise.
• Freeciv is a clone of the game Civilization
• Frozen Bubble, can be downloaded at http://www.frozen-bubble.org
• Several games are included in KDE, for instance
  • KAsteroids,
  • KAtomic,
  • KBounce
  • KSokoban,
• Liquid War is a multiplayer wargame available at http://www.ufoot.org/liquidwar/.
• NetHack is a popular free RPG available at http://www.nethack.org.
• Pingus, a Lemmings clone with animated penguins
• PlaneShift is a free and Open Source MMORPG in development.
• Raptor is a space shoot-em-up game at http://raptorv2.sf.net
• Reality-on-the-norm a bunch of user made adventure games downloadable from http://ron.the-underdogs.org/
• The Ur-Quan Masters, a GPL version of classic space adventure Star Control 2: http://sc2.sourceforge.net/
• Tux Racer, a 3D OpenGL racing game starring a penguin
• UFO2000 is a multiplayer remake of X-COM: UFO Defense at http://ufo2000.sourceforge.net/