Shooters

Zandronum
Free
Leading the way in newschool multiplayer Doom online.
Alien Shooter 2
Free
Xonotic
Free
An addictive, arena-style first person shooter with crisp movement and a wide array of weapons.
All Evil Night 2
Free
Meet monsters from your nightmares.
Unvanquished
Free
A free, open-source first-person strategy shooter, pitting technologically advanced human soldiers against hordes of highly adaptable aliens.
Counter-Strike 2D
Free
Free Top-Down Multiplayer Shooter.
Cube 2: Sauerbraten
Free
A free multiplayer & singleplayer first person shooter.
Invention 2
Free
Mechwarrior Online
Free
A tactical, 'Mech-based online shooter set in the rich BattleTech Universe.
Red Eclipse
Free
A free arena shooter featuring parkour.
Soldat
Free
An exciting unique side-view multiplayer action game.
3D Sniper
Free
Destroy the international terrorists camp that is based in eastern Africa.
Alien Arena
Free
A fast, fun, and free FPS deathmatch game!
All Evil Night
Free
AssaultCube
Free
A free, multiplayer, first-person shooter game.
Gnumz 2: Arcane Power
Free
Warsow
Free
A first-person shooter designed for online play.
3D Arcade FPS
Free
A free to play arcade first person shooter game, featuring: 6 mini arcade games, local / country / world high score YOU can be the country champion or perhaps even the world master.
Carnage Contest
Free
A free 2D turn-based multiplayer shooter with fully destructible terrain and an insane collection of weapons.
Invention
Free