The next chapter in the hit first-person shooter (FPS) series, Halo, will launch on September 22. Fans salivating for Halo 3: ODST right now, however, can pre-order the game forthwith and net an exclusive bonus for their salivated efforts.

Everyone who pre-orders Halo 3: ODST will be able to unlock Sergeant Avery Junior Johnson as a playable character when the game comes available.

Johnson, the classic cigar-chomping, tough-talking, battle-hardened, marine sergeant archetype and survivor of innumerable battles (naturally), has long been a favorite of Halo fans, though as a non-playable character (NPC). The pre-order promotion will mark the first time Johnson sees action as controlled by the gamer.

As a stand-alone expansion (i.e. original game not required to play) to the Halo universe, meanwhile, ODST will feature combat as an Orbital Drop Shock Trooper and reportedly help to flesh out some of the franchise's chaotic storyline by expanding on the events that occurred between the second and third games.

Like most Halo games, a strong multiplayer is component is expected. In addition to the single-player story mode, ODST players will be able to play co-operatively as squads fighting off waves of enemies together.

Halo 3: ODST will also give players early access to the beta for Halo: Reach, a prequel to the original trilogy, which is expected late 2010.