Shoot and survive

Free fast paced arena shooter

Tank digging battle game

Open source first person shooter

Dhewm 3 is a Doom 3 GPL source port

First-person shooter game

Epic story-driven FPS running on the Build Engine

A modernization effort of DOOM-3-BFG

A Quake mod based on the retro shooter SPRAWL

Open source first person shooter

The Free and Fast Arena Shooter

Open Source voxel shooter

Leading the way in newschool multiplayer Doom online

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

FPS aim trainer

Game engine for Classic Doom

Source port for Build engine games

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

Game engine for Return to Castle Wolfenstein

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

Fast paced, first person strategy game

EDuke32 is an awesome, free homebrew game engine

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

Free agile arena shooter

Classic arena first person shooter

A free first person shooter for Mac, PC and Linux

First-person shooter with cooperative in-game map editing

Top-down shooter action RPG

Modern cross-platform port of the Descent engine

ReC98 source port of the first Seihou Project game