First-person shooter game

A free first person shooter for Mac, PC and Linux

ReC98 source port of the first Seihou Project game

A modern cross‑platform port of “STAR WARS™: Dark Forces” with mod support

Open Source voxel shooter

Aliens vs Humans, First Person Shooter game with elements of Real Time Strategy

Leading the way in newschool multiplayer Doom online

Yamagi Quake II is an alternative client for id Software's Quake II

Source port for Build engine games

Top-down shooter action RPG

a modern QuakeWorld client focused on competitive online play

Modern cross-platform port of the Descent engine

Fast arcade first person shooter

The Free and Fast Arena Shooter

A modernization effort of DOOM-3-BFG

The orb ponderer's arena first-person shooter

A Zandronum 3.0 fork with improved netcode, configurable movement and many small tweaks

First-person shooter with cooperative in-game map editing

Dhewm 3 is a Doom 3 GPL source port

FPS aim trainer

Tank digging battle game

Free agile arena shooter

Classic arena first person shooter

Epic story-driven FPS running on the Build Engine

Shoot and survive

A Quake mod based on the retro shooter SPRAWL

Fast paced, first person strategy game

Game engine for Return to Castle Wolfenstein

EDuke32 is an awesome, free homebrew game engine

Open source first person shooter