ONI Alpha Site (Achievement)

ONI Alpha Site is an Achievement in Halo 3: ODST awarded for completing the Campaign mission ONI Alpha Site on normal or above and unlocks the Alpha Site map for Firefight. It is worth 30 Gamerpoints.

It is represented by an olive circle, with the Marathon symbol imprinted in it, with the remote detonator for an M165 Demolition Charge in front of it.