Free and open source first-person shooter

Cosmic horror first-person shooter

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

A modern port of the original Quake engine

Level editor for Quake-engine based games

A Quake mod based on the retro shooter SPRAWL

a modern QuakeWorld client focused on competitive online play

A free first person shooter for Mac, PC and Linux

Monitor and admin game servers

Level editor for ID Tech based games including Quake series