Shoot and survive

First-person shooter with cooperative in-game map editing

Modern cross-platform port of the Descent engine

Free fast paced arena shooter

Source port for Build engine games

Classic arena first person shooter

Top-down shooter action RPG

First-person shooter game

Game engine for Return to Castle Wolfenstein

Free agile arena shooter

A modernization effort of DOOM-3-BFG

a modern QuakeWorld client focused on competitive online play

Open source first person shooter

Leading the way in newschool multiplayer Doom online

The Free and Fast Arena Shooter

Open Source voxel shooter

Tank digging battle game

Game engine for Classic Doom

dhewm 3 is a Doom 3 GPL source port

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

EDuke32 is an awesome, free homebrew game engine

Epic story-driven FPS running on the Build Engine

Fast paced, first person strategy game

Open source first person shooter

The orb ponderer's arena first-person shooter

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

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

FPS aim trainer

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

A Quake mod based on the retro shooter SPRAWL