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

First-person shooter with cooperative in-game map editing

Shoot and survive

Classic arena first person shooter

A Quake mod based on the retro shooter SPRAWL

Open Source voxel shooter

EDuke32 is an awesome, free homebrew game engine

The orb ponderer's arena first-person shooter

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

Game engine for Return to Castle Wolfenstein

Modern cross-platform port of the Descent engine

Game engine for Classic Doom

Fast arcade first person shooter

Top-down shooter action RPG

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

Tank digging battle game

Dhewm 3 is a Doom 3 GPL source port

Free fast paced arena shooter

Fast paced, first person strategy game

a modern QuakeWorld client focused on competitive online play

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

Free agile arena shooter

Leading the way in newschool multiplayer Doom online

A free first person shooter for Mac, PC and Linux

The Free and Fast Arena Shooter

Open source first person shooter

FPS aim trainer

Open Source voxel shooter