ONI Alpha Site

ONI Alpha Site is the first one of the flashback levels in Halo 3: ODST. It is set in the ONI Alpha Base of New Mombasa.

The level opens two hours after the drop, and four hours before the Rookie's awakening, from Dutch's point of view, as he and Mickey set demolition charges to destroy the bridge leading to the complex to prevent the Covenant forces from accessing it. After destroying the bridge, they fall back into the facility.

Trivia

 * The Firefight map Security Zone is based on the level, namely the courtyard inside the wall surrounding the ONI building.
 * During the drop sequence when the player is in a HEV the ONI Alpha Site and its surroundings can be seen, including the bridge that is destroyed two hours later in this mission.
 * The NMPD Officer near the tower (the one talking to the Superintendent) is most likely a Captain as his suit differs from the others.
 * Joseph Staten stated that when the bridge blows up in Dutch's flashback, there's more to it, implying that Dutch and the marines are going to have to defend the base. Joseph said he wouldn't reveal much to the public.