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Release date: April 13, 2007 Sauerbraten / Cube 2
Sauerbraten, also known as Cube 2 or Sauer, is a partially (not all data is) free software/open source Quake-like first-person shooter computer game that runs on Windows, GNU/Linux, FreeBSD and Mac OS X. The game uses OpenGL and SDL, features single-player and multiplayer game play and contains a built in level editor.
CodeRED: Alien Arena (Alien Arena 2007) is a fully functioned free deathmatch shooter that runs on Windows and Linux, but not Mac, and features standard deathmatch, team deathmatch, capture the flag, Deathball, Team Core Assault, and All Out Assault, in a 50's era sci-fi atmosphere.