Quake 4 1.3 SDK

Quake 4 SDK contains the full public game source code, and map, mod and art samples.

About Quake 4:

Earth is under siege by the Strogg, a barbaric alien race moving through the universe consuming, recycling and annihilating any civilization in their path. In a desperate attempt to survive, an armada of Earths finest warriors is sent to take the battle to the Strogg home planet.

You are Matthew Kane, an elite member of Rhino Squad and Earths valiant invasion force. Fight alone, with your squad, or in hover tanks and mechanized walkers as you engage in a heroic mission to the heart of the Strogg war machine.

Battle through the beginning of the game as a combat marine, then after your capture, as a marine-turned-Strogg with enhanced abilities and the power to turn the tide of the war.

Built on id Softwares revolutionary DOOM 3 technology, QUAKE 4 also features fast-paced multiplayer competition modeled after the speed, feel, and style of QUAKE III Arena.