**ONI Alpha Site: know when to hold and when to get inside**

**ONI Alpha Site: know when to hold and when to get inside** *MCC walkthrough. Mission spoilers. Normal through Legendary.* ONI Alpha Site keeps giving you a position to defend and then taking it away. That is the important thing to understand before worrying about the weapons. You are not supposed to stand at the bridge forever, and retreating into the building is not a failed defense. It is the next objective. Dutch starts with the Spartan Laser and silenced SMG, with Mickey beside him. Keep the Laser for targets that justify the charge. Burning it on ordinary Grunts leaves you with a much worse answer when a Hunter or Wraith becomes the immediate problem. **Arm the bridge and pull back** Follow the markers to arm the remaining demolition charges, then retreat to the watchtower on the facility side and use the detonator. Get off the bridge before it goes. Staying behind to chase kills is particularly unwise because the sequence can advance without you personally deciding that you're ready. For an ordinary completion, destroying every Wraith at the far end is not the bridge objective. If surviving armor still has an angle on the defenders, the fixed Gauss weapons give you another way to deal with it without consuming all your Laser energy. The Wraith achievement changes this opening into a deliberate tank hunt. Decide whether you are doing that before advancing. Otherwise, follow Mickey through to the next defensive area. **Fight uphill, not in the landing zone** The exterior fight includes Hunters and successive Covenant reinforcements. Use the raised ground and solid structures to narrow the number of enemies that can fire on you. Don't stay down beside a fresh Phantom drop just because you have a heavy weapon. A Laser shot is valuable against a heavy target you can actually see. Step out, acquire the shot and return to cover; don't stand charging it while several different enemies shoot into your position. Use the SMG or an available replacement for the smaller enemies between those threats. On Legendary, remove exposed ranged threats before trying to circle a Hunter. Its partner is not the only thing that can kill you during the maneuver. Keep your retreat toward the building clear and avoid fighting so far forward that reinforcements cut you off from it. When the call comes to fall back, move. You do not need to prove that the outer courtyard belongs to you by remaining there after the objective has shifted indoors. **Defend the interior from both directions** Inside, the officers are preparing the building for demolition. Take the brief opportunity to check weapons, ammunition and nearby health before the next attack. If you want Fowl Hunt, obtain a shotgun from a shotgun-carrying ally with a normal weapon trade and save it for the roof. The sealed entrances will not stay sealed. Watch the left and right approaches and respond to the callouts. Suicide Grunts are a reason to shoot early and keep space between you and the doors, not a reason to rush in for melee kills. A turret can help thin a wave, but it also encourages tunnel vision. Check the other approach between bursts. If enemies reach your side of the room, leave the fixed position rather than trying to rotate through incoming damage. Once the first entrances are under control, more troops arrive from behind. Turn with the new threat. The room that was safe cover a moment ago is not automatically safe for the rest of the encounter. **Elevator, Drones and the roof** After the required defenders are cleared, return to Mickey and the elevator. Board and activate it. Keep a suitable small-arms weapon ready for the Drones during the ascent; a long charge with a heavy weapon is an awkward answer to several moving targets close by. The roof still has enemies on it. Clear the landing area, paying attention to the Jump Pack Brutes moving between positions. On Legendary, also account for the Chieftain rather than assuming the rooftop lineup is identical to Easy. If you're collecting Fowl Hunt, use the saved shotgun to finish three of the jetpack enemies before allies and the arriving Pelican remove the opportunity. For a plain completion, use whichever weapons let you clear the roof safely. Then **board the Pelican**. Surviving on the rooftop is not the final interaction. The mission ends when you get aboard and the evacuation sequence takes over. ONI is much easier to read when you treat it as a sequence of positions: bridge, outer defense, interior, elevator, roof. At each transition, reload and reassess. Carrying the habits of the previous fight into the next one is what gets an otherwise healthy run into trouble.