First-person shooter with cooperative in-game map editing

Classic arena first person shooter

EDuke32 is an awesome, free homebrew game engine

Fast arcade first person shooter

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

Open Source voxel shooter

Shoot and survive

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

A Quake mod based on the retro shooter SPRAWL

A Doom II mod with weapons and mechanics inspired by Quake Champions

Game engine for Classic Doom

A free first person shooter for Mac, PC and Linux

The orb ponderer's arena first-person shooter

Modern cross-platform port of the Descent engine

The Free and Fast Arena Shooter

Tank digging battle game

Top-down shooter action RPG

a modern QuakeWorld client focused on competitive online play

Game engine for Return to Castle Wolfenstein

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

ReC98 source port of the first Seihou Project game

Epic story-driven FPS running on the Build Engine

FPS aim trainer

Fast paced, first person strategy game

Free fast paced arena shooter

Dhewm 3 is a Doom 3 GPL source port

Open Source voxel shooter

Free agile arena shooter

Leading the way in newschool multiplayer Doom online

Open source first person shooter