A First Person Shooter that takes place on a Planet called Pandora. A fun thing about this game is the "87 Bazillion... Everything". That's actually an official advertisement by the way. Procedurally generated guns, shields, grenades, Relics, class mods, and more allow for just about anything to do just about anything.
Shotgun that shoots like a sniper rifle and electrocutes? Yup. Assault rifle that shoots explosive mini-rockets instead of bullets that coat enemies in acid? Gotcha covered. Grenades that explode into many more tiny grenades with homing and life-stealing? Sure. Shields that create a massive ring explosion of fire whenever they are depleted? Oh yeah.
I personally own it on Steam, but I believe it is available on the Xbox360 and Playstation 3 as well. Also Mac compatible (which, I'll be honest, I had no idea until I specifically searched for it).