Metropolis/Walkthrough

Ladies Like Superior Firepower
Take the “sixty-six tons of straight up, H-E-spewing dee-vine intervention” that Johnson gave you. The Warthog is nowhere near strong enough to survive the attacks you are about to face. Destroy all of the Ghosts that come your way. Be sure that they are completely destroyed—if you leave one alive, it will fire on you and you will have little chance of surviving. Take out the Wraith as soon as you have a clear shot. Be careful not to fall into the hole as you drive across the bridge. Take out Banshees as they fly by. Destroy anything at the tunnel entrance below, then look toward the skyscrapers because six Banshees will fly from them.

When the Banshees are scrap, drive into the tunnel. You will encounter minor resistance; take it out. When you reach the first partition, get out of your Scorpion (which should be nearly a wreck) and take the Marine's shotgun. Exchange it for whichever of your weapons is not the Battle Rifle.

The next section is full of infantry. Jump down and take cover behind the truck on the left side of the tunnel. Watch your motion tracker and put an 8 gauge into any enemy that comes to your side. (For most Elites, it will take 2.) Headshot the Jackal Snipers before they can kill you. Keep advancing through cover until you reach the next partition. Take a Jackal's Beam Rifle (in exchange for your shotgun), then enter the tunnel on the right.

This Town Ain't Big Enough For Both of Us
Assassinate the Jackal Sniper ahead of you. Stacker will ask you to get on the turret, but you will probably get sniped before you can. So instead, strafe behind cover, sniping Jackals as they show up. They are coming out of an alleyway, and they will continue to do so until you occupy it (a rare case of infinite enemies). Advance to this area, but take care not to get sniped. When you occupy it (and kill any remaining snipers), kill the rest of the Covenant. If the Warthog has not been destroyed, an Elite will probably have taken it—and he will fire the cannon at you. In that case, snipe him before he can kill you. Two Ghosts will show up; take them out.

In the next section, you will encounter the Wraith and more Ghosts. Grab a Rocket Launcher and put the Wraith out of commission, then destroy the Ghosts. If you run out of rockets, stick the Ghosts or snipe their drivers. Snipe the infantry near the waterfall.

Go behind the waterfall and give supporting fire to the Marines.

When the Ghosts are down, drive around the bend in the road. Kill the snipers on the half-bridge, then turn left. Use this path to flank the Wraiths. If you have a vehicle, get behind one of the Wraiths and start gunning it down. If you don't have one or would like to upgrade yours to a Wraith, try to flank it without being noticed, then get on the hatch (not the back) and melee until the Wraith is yours (don't plant any grenades). Let the other Wraith fall to your plasma mortar or whatever you have. Then deal with the minor threats.

Once the Wraiths are scrap (or one is and you are driving the other), go into the hallway and follow Perez to the balcony.

Field Expedient
Once the Scarab passes, go into the building behind you and up the ramp. At the top, you will see the Scarab again.

Bombard the deck with all of the HEAT missiles around. Once those are used up, snipe anyone remaining on the deck, then grab a shotgun and jump on board. Enter the control room and stick the Elites. Use your shotgun to kill anyone who survives and end the level.