The M90 Shotgun is the resident UNSC close combat weapon. Because of its extreme stopping power, the M90 is often wielded in tight or confined conditions, where the close ranges are conducive to the shotgun's mode of operation. It is, however, a very large and heavy weapon.

NOTE: A Bungie fan favorite since the WSTE-M of Marathon 2, we can only hope that the shotgun returns to its glory of Halo 1 as an absolutely deadly close quarter weapon. In Halo 2, at times it was more effective when intentionally aimed off-target, even with little to no lag involved, due to the weapon's spread pattern. While the above text lists size and weight as tradeoffs, these are not gameplay considerations as Halo does not consider encumbrance.

This weapon's appearance and designation (M90) are identical to the SMG's in Halo 2, which would seem to indicate minimal, if any, changes.

UPDATE: Shotgun fans, your boat has come in. In the public beta, the shotgun just works. Just aim and fire; at close range, if your target is in the reticle, they are dead. End of story.