ONI Alpha Site/Walkthrough

From Halopedia, the Halo wiki

After the cutscene ends, immediatley aim your Spartan Laser at the Wraith to take it out. You should have 3/10 of the progress needed for the achievement. Take out the other Wraith to the left so it wont give you any trouble, now try and use the Shoot-thru multi-kill method of the Spartan Laser. You should be able to shoot through a Brute, killing a few Grunts following him. You should have the achievement now, continue to the end of the bridge. The Cop and Superintendant argue about, then it accepts the Cop's sentence. Head up the tower, there is a Sniper Rifle, trade the Laser for it if you're out of ammo. After blowing the bridge, head into the complex's entrance. Kill the couple of Grunts and Brutes, be warned about the Hunter Major, he can kill you off-gaurd. After clearing everything, there are some Jump Pack Brutes inside, after clearing everything, head up the elevator with the Cops. There are Drones that come up from below, make sure you've got an automatic weapon to take them down. After reaching the top, there are some Brute Captains with Brute Shots. Take them out cautiously, use grenades for the Grunts. You may want to trade your weapon for a Cop's Shotgun, as it is useful at this part for taking out these High Ranked Brutes. An NMPD Pelican will swoop in, there is a Cop on an HMG, he could be of help. After that, board the Pelican and you're done. Watch the Superintendant get angry as the building blows and the Pelican flies away.