Shoot and survive

Free fast paced arena shooter

Open Source voxel shooter

Modern cross-platform port of the Descent engine

dhewm 3 is a Doom 3 GPL source port

The Free and Fast Arena Shooter

First-person shooter game

Open source first person shooter

Top-down shooter action RPG

Epic story-driven FPS running on the Build Engine

Source port for Build engine games

A modernization effort of DOOM-3-BFG

Game engine for Return to Castle Wolfenstein

First-person shooter with cooperative in-game map editing

Classic arena first person shooter

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

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

Leading the way in newschool multiplayer Doom online

Game engine for Classic Doom

Free agile arena shooter

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

EDuke32 is an awesome, free homebrew game engine

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

A Quake mod based on the retro shooter SPRAWL

Fast paced, first person strategy game

a modern QuakeWorld client focused on competitive online play

FPS aim trainer

Open source first person shooter

Tank digging battle game

The orb ponderer's arena first-person shooter