A free first person shooter for Mac, PC and Linux

First-person shooter game

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

Leading the way in newschool multiplayer Doom online

Open Source voxel shooter

Source port for Build engine games

ReC98 source port of the first Seihou Project game

The Free and Fast Arena Shooter

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

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

Top-down shooter action RPG

Classic arena first person shooter

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

Fast paced, first person strategy game

Fast arcade first person shooter

Modern cross-platform port of the Descent engine

A modernization effort of DOOM-3-BFG

First-person shooter with cooperative in-game map editing

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

a modern QuakeWorld client focused on competitive online play

The orb ponderer's arena first-person shooter

Free agile arena shooter

EDuke32 is an awesome, free homebrew game engine

Tank digging battle game

FPS aim trainer

Game engine for Return to Castle Wolfenstein

Dhewm 3 is a Doom 3 GPL source port

Free fast paced arena shooter

Epic story-driven FPS running on the Build Engine

A Quake mod based on the retro shooter SPRAWL