Epic story-driven FPS running on the Build Engine

Fast paced, first person strategy game

Tank digging battle game

Source port for Build engine games

Free fast paced arena shooter

First-person shooter game

Leading the way in newschool multiplayer Doom online

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

Game engine for Return to Castle Wolfenstein

The Free and Fast Arena Shooter

Open Source voxel shooter

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

Classic arena first person shooter

Game engine for Classic Doom

Free agile arena shooter

Dhewm 3 is a Doom 3 GPL source port

Open source first person shooter

FPS aim trainer

EDuke32 is an awesome, free homebrew game engine

Modern cross-platform port of the Descent engine

A Quake mod based on the retro shooter SPRAWL

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

Shoot and survive

First-person shooter with cooperative in-game map editing

The orb ponderer's arena first-person shooter

Open source first person shooter

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

a modern QuakeWorld client focused on competitive online play

A modernization effort of DOOM-3-BFG

Top-down shooter action RPG