According to research group OTX, this expansion tops the list of most-wanted Xbox 360 games, barely edging out Infinity Ward's Modern Warfare 2. Gamasutra: Halo 3: ODST Tops Most-Wanted Xbox 360 List (April 29, 2009)

1. New extended campaign with four player co-op
2. New hero (UNSC Orbital Drop Shock Trooper)
3. Stealthier gameplay
4. Additional hours of singleplayer and multiplayer gameplay
5. Ships with all 24 Halo 3 multiplayer mapsTeamXbox: Halo 3: ODST to Include All Halo 3 Multiplayer Maps (February 9, 2009)
6. More mutliplayer features including new maps and full forge optionsIGN: TGS 2008: Halo 3: Recon Facts (October 9, 2008)

Halo 3: ODST takes place in between the events of Halo 2 and Halo 3, and puts the player in the role of a lone Orbital Drop Shock Trooper (ODST) who is wandering through the wartorn city of New Mombasa in search of the other members of his squadron. The ODST trooper isn't equipped with the Spartan armor that the Master Chief has, so combat is more methodical and defensive than it is in the other Halo games.

As the ODST trooper discovers clues about his comrades, the game will cut to a playable sequence that unfolds from the perspective of that soldier, rounding out the story of what happened in New Mombasa from multiple perspectives.

ODST will also include new multiplayer maps for Halo 3.