Source port for Build engine games

a modern QuakeWorld client focused on competitive online play

Free fast paced arena shooter

Epic story-driven FPS running on the Build Engine

First-person shooter game

Game engine for Classic Doom

Open Source voxel shooter

Top-down shooter action RPG

Fast paced, first person strategy game

Shoot and survive

Free agile arena shooter

Open source first person shooter

First-person shooter with cooperative in-game map editing

Tank digging battle game

Classic arena first person shooter

The orb ponderer's arena first-person shooter

A free first person shooter for Mac, PC and Linux

Dhewm 3 is a Doom 3 GPL source port

Modern cross-platform port of the Descent engine

Leading the way in newschool multiplayer Doom online

The Free and Fast Arena Shooter

A modernization effort of DOOM-3-BFG

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

ReC98 source port of the first Seihou Project game

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

Game engine for Return to Castle Wolfenstein

FPS aim trainer

EDuke32 is an awesome, free homebrew game engine

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

Open Source voxel shooter