Shoot and survive

ReC98 source port of the first Seihou Project game

Free fast paced arena shooter

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

First-person shooter game

Fast paced, first person strategy game

Epic story-driven FPS running on the Build Engine

Open Source voxel shooter

The Free and Fast Arena Shooter

A modernization effort of DOOM-3-BFG

Game engine for Classic Doom

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

Classic arena first person shooter

dhewm 3 is a Doom 3 GPL source port

FPS aim trainer

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

Game engine for Return to Castle Wolfenstein

Free agile arena shooter

Leading the way in newschool multiplayer Doom online

Open source first person shooter

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

Tank digging battle game

Source port for Build engine games

Modern cross-platform port of the Descent engine

Top-down shooter action RPG

EDuke32 is an awesome, free homebrew game engine

Open source first person shooter

a modern QuakeWorld client focused on competitive online play

First-person shooter with cooperative in-game map editing

The orb ponderer's arena first-person shooter