Epic story-driven FPS running on the Build Engine

Dhewm 3 is a Doom 3 GPL source port

Free agile arena shooter

The Free and Fast Arena Shooter

Classic arena first person shooter

Source port for Build engine games

Open Source voxel shooter

Fast arcade first person shooter

EDuke32 is an awesome, free homebrew game engine

Leading the way in newschool multiplayer Doom online

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

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

A Quake mod based on the retro shooter SPRAWL

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

FPS aim trainer

Fast paced, first person strategy game

First-person shooter game

A Doom II mod with weapons and mechanics inspired by Quake Champions

Free fast paced arena shooter

Tank digging battle game

Game engine for Classic Doom

Open Source voxel shooter

a modern QuakeWorld client focused on competitive online play

A modernization effort of DOOM-3-BFG

The orb ponderer's arena first-person shooter

Game engine for Return to Castle Wolfenstein

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

ReC98 source port of the first Seihou Project game

Open source first person shooter

Top-down shooter action RPG