The Evil (part 2) addon - Quake 4

In 1997 Quake II was released ending the Strogg's collective leader the Makron being killed. Quake III moves away from the Strogg, but the universe's worst cybernetic foes return in Quake IV, ready to be destroyed yet again by Earth's forces. Quake II left the Strogg home planet without its planetary defenses, leaving it open for your attack as part of Earth's new armada. You help deliver the final assault to the Strogg as Matthew Kane, member of an elite squad fighting along squadmates with vehicles and advanced weaponary. Quake IV is based on the Doom III engine, although it is apparent that Quake IV will be a superior modding platform thanks to iD and Raven's efforts in optimizing the netcode, adding vehicles, and general fixes made to the engine since Doom III's release.