Free fast paced arena shooter

Top-down shooter action RPG

Shoot and survive

Open Source voxel shooter

First-person shooter game

Dhewm 3 is a Doom 3 GPL source port

Open source first person shooter

Tank digging battle game

Epic story-driven FPS running on the Build Engine

Leading the way in newschool multiplayer Doom online

The Free and Fast Arena Shooter

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

Open source first person shooter

Modern cross-platform port of the Descent engine

FPS aim trainer

A free first person shooter for Mac, PC and Linux

Game engine for Classic Doom

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

Fast paced, first person strategy game

A Quake mod based on the retro shooter SPRAWL

Open Source voxel shooter

A modernization effort of DOOM-3-BFG

EDuke32 is an awesome, free homebrew game engine

First-person shooter with cooperative in-game map editing

Game engine for Return to Castle Wolfenstein

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

Classic arena first person shooter

Source port for Build engine games

The orb ponderer's arena first-person shooter