AssaultCube, formerly ActionCube, is a free first-person-shooter based on the game Cube.
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Tremulous is a free, open source game that blends a team based FPS with elements of an RTS.
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Cube 2: Sauerbraten is a free multiplayer/singleplayer first person shooter, built as a major redesign of the Cube FPS.
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Alien Arena is a fast paced, furious frag fest with arenas ranging from the small, to the massive.
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Nexuiz is a free open-source first person shooter that runs on Windows, Linux and OSX.
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Smokin' Guns is intended to be a semi-realistic simulation of the "Old West's" great atmosphere & was developed on Id Software's Quake III Arena Engine.
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Paintball2 is a fast-paced first-person game with capture the flag, elimination, siege, and deathmatch (free-for-all) styles of gameplay.
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Blood Frontier is a Free and Open Source game , using SDL and OpenGL which allows it to be ported to many platforms.
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OpenArena is a community-produced deathmatch FPS based on GPL idTech3 technology.
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