Halo 3: ODST marks a couple of firsts in the series. The first is the fact that you don't play as Master Chief. Instead, you assume the role of The Rookie, an ODST (Orbital Drop Shock Trooper) who may not be as big and bad as a Spartan, but is definitely capable of handling himself when there's a fight going on. The second is Halo 3: ODST's non-linear story. The last is an all-new co-op multiplayer mode called FireFight where instead of teabagging players from around the world, you can collectively teabag a grunt or two.