ReC98 source port of the first Seihou Project game

Open Source voxel shooter

Source port for Build engine games

First-person shooter game

Epic story-driven FPS running on the Build Engine

Lo sparatutto arena libero e veloce

Leading the way in newschool multiplayer Doom online

EDuke32 is an awesome, free homebrew game engine

Free agile arena shooter

Open source first person shooter

Game engine for Classic Doom

Classic arena first person shooter

Free fast paced arena shooter

a modern QuakeWorld client focused on competitive online play

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

FPS aim trainer

Modern cross-platform port of the Descent engine

Game engine for Return to Castle Wolfenstein

Shoot and survive

Dhewm 3 is a Doom 3 GPL source port

Open source first person shooter

A modernization effort of DOOM-3-BFG

The orb ponderer's arena first-person shooter

A Quake mod based on the retro shooter SPRAWL

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

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

Top-down shooter action RPG

Tank digging battle game

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

Fast paced, first person strategy game