Nine Inch Nails front man and lifelong gamer Trent Reznor, who worked with id Software on the music for Quake and Doom 3, is back into game music, composing the theme for Treyarch's upcoming Call of Duty: Black Ops 2.Reznor, who has played such games as Diablo III, Heavy Rain and Skyrim, is also a fan of the Call of Duty franchise, according to an interview in USA Today.