Halo Alpha
Halo Alpha


Fall back, deny access to this vital facility.

ONI Alpha Site[1] is the sixth campaign level of Halo 3: ODST. It is set in the ONI Alpha Site in New Mombasa.

The level is set two hours after the Squad's drop into the city, and four hours before the Rookie's awakening, from Dutch's point of view. He and Mickey are defending the ONI facility with the help of the city's Superintendent, NMPD, and Marine forces.

Completing this level on Normal or above unlocks the ONI Alpha Site achievement as well as the Firefight map Alpha Site.


The level opens as Mickey and Dutch are setting demolition charges to destroy the bridge leading to the complex to prevent the Covenant forces from accessing it. After the charges are armed, an NMPD officer commands the Superintendent to unlock a keypad on a bridge toll booth so they can remotely detonate the charges. The AI is hesitant at first, but eventually lets Dutch destroy the bridge. After this, they fall back deeper into the facility, fighting off more waves of Covenant until they are forced to retreat into the ONI building itself. Dutch and the NMPD officers fight off the squads of Brutes, Grunts and Jackals that continue to push into the building. Eventually the fight is brought up to the roof of the facility, where the final Covenant infiltrators are killed. A Pelican picks up Dutch and Mickey, and the level ends as Mickey remote detonates the charges in the ONI facility, destroying it, and awakening a Drone Hive below.




ONI Alpha Site

2 hours after drop

Dutch watches as a Wraith moves into position, while Mickey arms a detonator.

The Wraith starts to open fire.

  • Mickey: "Look, if you wanna do this be my guest. But this, ain't... (presses button) a job you wanna rush."

Mickey finishes arming the detonator.

  • Dutch: "That do it?"

Dutch looks down the bridge to a watchtower with an NMPD Officer in it, which almost gets hit by a plasma mortar.

  • NMPD Officer: "Signal's good! (Large explosion) Arm the other detonators and pull back to me!"
  • Mickey: "Come on, tough guy, we gotta blow this bridge."

The two run down the bridge, another Wraith moves in and starts to fire.

The view switches to Dutch, who takes cover behind a destroyed Warthog, a plasma mortar lands a few feet in front of him.

  • Mickey: "Dutch, arm the other charges!"

Dutch looks back at the Wraiths starting to move up to the bridge.

  • Dutch: "What about those Wraiths?"
  • Mickey: "Forget about 'em, we got explosives to set!"


  • Mickey: "Follow me, arm the charges!"

A squad of Marines are trying to hold the Covenant back.

  • Marine: "We'll never stop that armor! Fall back!"

If Dutch turns to fight the advancing Covenant horde:

  • Mickey: "Dutch, ignore those tanks!"

If Dutch walks past the first charge:

  • Mickey: "I got this one, Dutch, you do the rest!"

If Dutch walks past the second charge:

  • Mickey: "Great, I got to do everything myself?"

After the second charge is armed, two Banshees join the fight.

  • Mickey: "That's the last one Dutch! Everyone, behind those barriers, bridge is set to blow!"

If Dutch doesn't go up the ladder to the tower

  • Mickey: "Watchtower Dutch, get up there and pull the trigger!"

Dutch heads for the tower and goes up the ladder.

  • NMPD Officer: "Come on, Super, unlock the keypad!"
  • NMPD Officer: "If you don't let us trigger those charges, in about five minutes, your data center's going to be crawling with Covenant!"

The Superintendent gives off a chime.

  • NMPD Officer: "About damn time! Do it trooper!"

If Dutch doesn't trigger the charges yet:

  • NMPD Officer: "Trooper, use the laptop to trigger the charges!"

If Dutch further stalls:

  • Mickey: "What's the hold up, Dutch? Blow this sucker sky high!"

If some Covenant succeeds in crossing the bridge:

Marine: Kill their infantry! Don't let them cross the bridge!

Dutch or the NMPD Officer triggers the charges:


The bridge is destroyed, killing all Covenant troops still on the bridge.

  • Mickey: "Woo-hoo! Yeah! That's the way."

Mickey, Dutch, the Marines and the NMPD Officer make their way under the wall.

  • Mickey: "Aw man, Covenant landing on the other side of the wall!"

If Dutch doesn't go under the wall:

  • Mickey: "C'mon Dutch, those cops aren't going to last long against Brutes!

If Dutch still doesn't follow Mickey:

  • Mickey: "Over here Dutch, into the tunnel, under the wall!"

The group make their way up the stairs, to the courtyard.

  • Mickey: "Go, Dutch! We gotta keep the Covenant away from that building."

Mickey and Dutch make their way up the hill, which is being defended by more NMPD Officers and Marines.

  • Female Marine: "All teams, hold the ridge, don't let them near the ONI building!"

Soon, more and more waves of Covenant are dropped off.

  • Female Marine: "Fall back! I repeat, fall back to the top of the ridge!"
  • Jiralhanae Captain: "Courage, warriors! Take this hill or DIE UPON IT!!!"


  • Jiralhanae Captain: "Forward! Grind their bones beneath your feet!"
  • Mickey: "More Phantoms, look sharp!"
  • Female Marine: "We can't hold 'em, every one fall back inside the building!"
  • Mickey: "Dutch, inside the building! NOW!"

The ODSTs retreat into the building's interior. NMPD Officers go outside in a last effort to hold back the Covenant. Dutch and Mickey go to a group of officers in the center of the complex.

  • NMPD Sergeant: "Hurry up men, check those charges!"
  • Mickey: "Wait, what? More explosives?"
  • Dutch: "Yeah, what gives? I thought we were supposed to protect this building?"
  • NMPD Sergeant: "I have orders to deny enemy access to all classified data housed in this facility. You don't like it, jump your butts back into orbit!"
  • Mickey: "The only thing I don't like, is that our butts are currently inside this facility."

(Cutting noises and sparks appear on the sealed doorways.)

  • NMPD Officer: "They're cuttin' through the door."
  • NMPD Sergeant: "Settle down people, find some cover. Someone man that turret."

The doors explode. Brutes can be heard giving out battle cries.

  • NMPD Sergeant: "Alright, here they come. Watch your crossfire people."

During this Mickey and the Sergeant will say various lines, so the player knows to change direction.

  • NMPD Sergeant: "Where's that fifty? We got hostiles right!"
  • NMPD Sergeant: "They're comin' in on the left, adjust your fire!"
  • Mickey: "Dutch, scan right!"
  • Mickey: "They're pouring into the left!"
  • Mickey: "Right side, Dutch!"
  • NMPD Sergeant: "Left side trooper! Bring that turret round"!

After defeating a few waves, the Covenant start dropping in troops behind Dutch and Mickey.

  • NMPD Sergeant: "Phantom dropping reinforcements, cover your rear trooper!"

Soon the Covenant reinforcements are defeated.

  • Mickey: "That's the last of 'em Dutch, come back to my position!"

An NMPD Officer arrives with an elevator.

  • NMPD Officer: "Everyone in the elevator, I put enough charges in this shaft to blow this building twice!"
  • Mickey: "Alright, that's it. Transfer the detonation codes to my COM. If anyone's takin' this place out, it's gonna be me."

Dutch activates the elevator, and they slowly make their way up.

NMPD Officer: "Evac bird's gonna meet us on the roof."

With IWHBYD skull activated

Mickey: "I love blowing crap up Dutch, but this situation sucks.

However, on the way up they are soon engaged by a swarm of Yanme'e.

  • Dutch: "Where the heck did these buggers come from?"
  • NMPD Officer: "Underground tunnels are filled with the damn things!"
  • Mickey: "Finally, a good reason to blow this building up!"

They soon defeat the Drones and make it to the roof, where a Phantom is dropping off a pack of Jump Pack Jiralhanae.

After the Phantom leaves, the evac Pelican arrives, and helps the ODSTs with the enemy reinforcements, which are soon defeated.

  • Mickey: "There's our ride, go! Go! Go!"

If the player doesn't board it:

  • Mickey: "Let's get outta here Dutch come on!

If the player still doesn't board it:

  • Mickey: "Building's lost. Nothing more we can do."

If the player still doesn't board the Pelican:

  • Mickey: "Dutch, I thought you wanted to leave."

or, with IWHBYD skull on:

  • Mickey: "Dutch, you dumbass, get aboard!"

As soon as the player boards the Pelican, the level ends.


Mickey and Dutch board the Pelican, remove their helmets and take a seat. The NMPD officer on board looks at them.

  • Mickey: "Sure do!"
  • NMPD Officer: "Patching him through."

The Pelican lifts off and departs the ONI building

  • Buck: "Glad you boys are safe and sound."
  • Dutch: "Likewise Gunny, you need a pickup?"
  • Buck: "Long as you're offerin'. We're in the Police HQ."
  • Dutch: (to the NMPD Officer) "Can you take us there?"
  • NMPD Officer: "Affirmative!"
  • Buck: "Alright, meet you up top!"

Mickey nudges Dutch

  • Dutch: "What?"

Mickey points to the ONI Building, and starts to count down from three on his fingers. When he reaches zero, he detonates the charges, destroying the building.

  • Mickey: (laughs) "This day ain't turnin' out so bad after all!"
  • Dutch: "Heh."

The Pelican flies away as the view changes to a Superintendent camera, the avatar gives a confused then angry face as the building is destroyed.

The cutscene ends. Screen fades to black.


  • During the drop sequence when the player is in their Pod the ONI Alpha Site and its surroundings can be seen, including the bridge that is destroyed two hours later in this mission.
  • If you don't arm the explosives and instead kill all of the Covenant on the bridge, Mickey will arm the charges and the NMPD Officer will blow it instead, even if you're still on the bridge and it is cleared of all Covenant.
  • If playing on Co-op with campaign scoring active, the host will receive points for any Covenant who are killed by the bridge's detonation, often resulting in large multi-kills such as Killpocalypse or Killionaire.
  • Inside the base is a memorial wall with hundreds of names of the people who have died in the war. Dr. Catherine Halsey and Admiral Preston Cole are listed, along with some humorous names, like London Bridges.
  • At the part where you have to defend until the elevator comes, if you jump over the walls (where the elevator comes up) and fall to the bottom then go into theater and go to the bottom you will see an unarmed M168 Demolition Charge, this is either a glitch or an Easter egg, it is still odd for it to be the only one in the shaft. It is also on the Firefight map Alpha Site, (unarmed, green, red, armed). It is mostly likely an easter egg or an item Bungie left by accident.
  • The beginning of the level up to the bridge explosion was the first level shown at E3 2009.
  • The NMPD officer in charge of the group Dutch and Mickey team up with in the main hall of the ONI site has glasses which will read either "Keep it Clean" or "Please remain calm" running across them in a loop (best seen using Theater).
  • You can get outside the level in theater mode by flying to the left of the building before the game loads the second section of the level.
  • At the part where you are inside the ONI building with the Kamikaze Grunts, if you kill one while it is near the other, (a better chance of getting this with the Mythic Skull on) sometimes the grenades will drop out of its hands and it will be unarmed.
  • In the level Data Hive, when Dare says "Some idiots blew the building at the top of the shaft," she is referring to the destruction of the ONI building in this level.
  • The Officer in the tower is almost invincible, being able to withstand several spartan laser shots, sniper rifle rounds, even the odd Wraith shot.
  • If a Marine is near the bridge when it explodes, if they don't die, they will be thrown quite far, and in rare cases will be thrown through the wall.
  • For some reason, no Marines will go inside of the ONI building, even if you manage to kill all the enemies and keep a Marine alive. This may be a game error since you can see NMPD Officers going inside, however the Marines may have stayed outside to hold off the approaching Covenant troops.
  • If you activate the elevator and then jump over the railing you can see the drones spawn or go hide in another area of the level, then when the elevator reaches the top you will teleport into it. This can be quite useful on Legendary if you have trouble fighting Drones.
  • This is the last level you are aided by normal Marines.
  • The Marines on the bridge are usually weaker than the ones near the building, and are usually killed as they descend the steps to the courtyard.
  • Strangely, The Superintendent places beacons on the charges but initially refuses to allow Dutch to destroy the bridge.
  • At some points, the Marine who gives the commands to retreat will be invincible, capable of withstanding several blows from a gravity hammer.
  • The debris on the bridge simply fall into the water when the bridge is destroyed, instead of being propelled into the air.
  • The Firefight level Alpha Site is based on this level and unlocked by completing this level. Security Zone is also based on this level.
  • At the end of the mission, Mickey does a countdown with his fingers before the site blows up. This is a reference to the film "Starship Troopers: Invasion" Where the character Mech does the same thing.