Top Alternatives to Tremulous

Counter-Strike is a series of multiplayer first-person shooter video games, in which teams of terrorists and counter-terrorists battle to, respectively, perpetrate an act of terror and prevent it.

Quake is a series of first-person shooter video games, starting with the game of the same name.

Xonotic is a free and open-source first-person shooter video game.

Doom is a series of first-person shooter video games.

Cube 2: Sauerbraten ("sour roast", or Sauer) is a cross-platform, Quake-like first-person shooter that runs on Microsoft Windows, Linux, FreeBSD and Mac OS X using OpenGL and SDL.

OpenArena is a free and open-source video game, it is first-person shooter (FPS) and a video game clone of Quake III Arena.

Urban Terror is a freeware multiplayer first-person shooter video game.

Red Eclipse is a fun-filled new take on the first person arena shooter, built as a total conversion of Cube Engine 2.

Nexuiz is a multiplayer first-person shooter. It is distributed under the GNU General Public License (GPLv2).

AssaultCube (ActionCube) is a free and open source software first-person shooter video game.

Warsow, also stylized as War§ow, is an open source first-person shooter video game.

Dead Space is a series of horror games.

Unvanquished is an opensource first-person strategy shooter game.

Alien Arena is a fast, free FPS deathmatch game.

AU Modern FPS is a browser-based game.