ONI Alpha Site is an Achievement in Halo 3: ODST and Halo: The Master Chief Collection. It is obtained by completing the Campaign mission ONI Alpha Site on normal or above and unlocks the Alpha Site 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.
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