A Quake mod based on the retro shooter SPRAWL

Game engine for Return to Castle Wolfenstein

The orb ponderer's arena first-person shooter

Open Source voxel shooter

Shoot and survive

First-person shooter game

Leading the way in newschool multiplayer Doom online

Free fast paced arena shooter

Top-down shooter action RPG

Free agile arena shooter

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

The Free and Fast Arena Shooter

Source port for Build engine games

A modernization effort of DOOM-3-BFG

Dhewm 3 is a Doom 3 GPL source port

Epic story-driven FPS running on the Build Engine

Tank digging battle game

Game engine for Classic Doom

Fast paced, first person strategy game

FPS aim trainer

Open source first person shooter

Modern cross-platform port of the Descent engine

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

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

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

A free first person shooter for Mac, PC and Linux

Classic arena first person shooter

ReC98 source port of the first Seihou Project game

Open Source voxel shooter

Open source first person shooter