In 2001 Jesse Lacey, the pale poster boy of emo, crooned about mixtapes. Mixtapes, in this case, were artfully-compiled collections of songs stitched together for another person. They were the burned CDs you'd slide in the locker of a crush in high school or the cassette tapes obsessed over in a Nick Hornby novel. These days, mixtapes are somewhat obsolete given digital playlists. But the mixtape format is finding new life in video games.