"In Quake 4 the Strogg are quickly regrouping, however the Strogg’s planetary defenses still destroyed, Earth's forces can deliver a full and final assault. This time, you're not alone. You are Matthew Kane, an elite member of Rhino Squad, and part of Earth’s next invasion wave. An army of soldiers are fighting with you and an arsenal of weapons and vehicles are at your disposal in this heroic and epic battle between worlds."
Some good information and photos,
check it out.