- Assault Rifle
- Plasma Rifle
- Rocket Launcher
- Plasma Pistol
- Plasma Grenade
- Fragmentation Grenade
And The Horse You Rode OnEdit
Move down the path until you find a small entryway into the vents. Proceed inside and search for a ladder in the floor. You'll see Infection Flood popping out of the hole. Spray them with the Rifle, then drop a grenade in the hatch to take down the Carrier below. Then follow the ladder down. You'll be greeted by Sentinel lasers. Drop them, then turn the corner, following the path until it appears to dead end. It isn't a dead end, though. Soon, a door will spring open and Flood will stream out. Fall back and waste them, then make your way through the door they burst open.
Keep moving down the path, removing enemies and generally kicking ass until you reach a flaming mass to the right. Move through the green-lit door ahead. In the hallway that bisects it, you'll see a Hunter on either side. Use grenades and your Assault Rifle to take them down, making sure you don't go after one and leave your back open to the other. When both are dead, search the locker room in this hallway for Shotgun ammo, grenades and health packs. Then enter one of the two doors that lead into the cafeteria.
There are a whole lot of baddies on the opposite side of this room. Elites. Armored Elites. Enemies who like to throw grenades. Always keep a path clear to retreat, because you'll have to fall back a lot to avoid grenade throws. Be very methodical and patient with this room. There's no reason to rush. Throw your own grenades, wait for good shots and pick off the Elite one by one. If you take a shield hit, fall back and regenerate. If you really get dinged, go back to the locker room and grab another health pack.
When all of the Elite fall, move through the room to the far left corner. Blast the annoying Grunts with the green energy rifles, then fall back and let them explode. Move across the next hallway into a narrow maintenance passage. Here, you'll find another batch of Elite. Smite them with the mighty Shotgun and continue to the bridge area. Here, a cutscene will trigger. You have set the self-destruct sequence in motion, only to have the Monitor thwart your plans. Time to do it yourself...
When the cutscene concludes, shoot down the Sentinels that appear. Or don't. Head back the way you came. There will be a door open that wasn't previously. Flood are waiting there to kill you. Teach them that's a bad idea. Smoke them then move through the room they came from... it's an armory.
Head to the door at the end of the room and go through. There's a pair of big, bad Hunters off to the right. Move straight past them into the passage ahead, then move through a couple sets of doors to find some Sentinels and Flood battling. Move forward and finish them off, then duck under a half-closed door on the left side of the hall. More Sentinels wait in the passage ahead. Smoke them, then move through the door here. In the next hall, you'll see a yellow arrow on the floor pointing toward the Cryo Bay. Move into the room to find a group of Sentinels hosing down the Flood. Slay anything that moves, then head to the far end of the room and climb the ladder here.
Take down the Sentinels in the glassed-in observatory deck above, then get ready for a slew of Flood from the left. Drop them as they attack, then move down this passage. The path will eventually dump into a long, gray hall. Stay there for a second and prepare for another Flood attack, this time from the door on the opposite side of the passage. Once you wipe out the Flood that charge, move forward into the area they vacated and grab the Overshield here. Return to the gray hall and move left, toward a bunch of toppled debris. Here, you'll find a door into the air vents. Go through.
Follow the narrow passages until you reach a small, grated green door. In the destroyed area back here, you'll see plenty of corpses and plenty of grenades. Grab what you can, then head back into the vents. When you enter these tunnels again, take the first left into the hallway, then quickly duck back into the tunnel. There's tons of everything in the passage you just tiptoed into—Sentinels, Elite, Flood, Hunter. The fight will rage on without you, so let it. There are several routes into the passage to the left in addition to the one you just used. Move to the opposite end to find a health pack and bundle of Frag grenades near a sealed-off door. Then move over one more and hang out near the edge of the corridor. If you look to the right, you'll see Hunters and Elite. If you look to the left, you'll see Sentinels and Flood.
Take down the Elite and Hunter if you wish, otherwise, just torque into the hallway, take a right and leave all of the nonsense behind. While it's fun to contribute to this fight, it has nothing to do with you. Follow the path until you see the path to Engineering. Then follow the path forward until you reach a crossroads.
Light Fuse, Run AwayEdit
In the following areas, you will meet with lots of Flood. Move forward on the path to reach the Engine Room. Once inside, head up the ramp here. You'll notice tons of health packs on sections of wall on this level. Remember these, you'll need them if you get beat up in battle.
Proceed to the door that says Level 2, then work your way up the winding ramp. On the next level, make your way to the Level 3 door. You'll have to battle through some Flood to get up to the level you need, but once you do, make your way to the nav point. On the ledges here, you'll note a couple control panels. Move to one and press X to open the exhaust vent core. You'll see the long beams below you begin to retract. Drop on to another one of the beams that run across the room, then aim at the opened core and either shoot a Rocket or toss a Grenade inside. Repeat this process for both manifolds on this side, then return to the previous hallway and move to the other side of the engine room. This will help you get at the remaining nav points. You'll have to dodge fire from Sentinels and Flood during your explosion attempts, so stay on your toes and monitor the shield level.
Warning: Hitchhikers May Be Escaping ConvictsEdit
As soon as the elevator stops, rush for any Warthog, your choice as to which. Stick to one you can quickly get into and drive out, and try to stick to the same one every run for practice. The one immediately to the right has a small tunnel conveniently leading to the driver seat. If doing Co-op, having the second person go in the passenger seat is preferred, as one in the turret will actually change the balance of the jeep and change the physics of jumps.
Note that it is possible with one in the turret (the gunner also gives more protection from enemies) but many of the fine details are based on a single player (or driver/passenger) run.
On the first hill going up, careful to evade the plasma grenade the elite throws as it will kill, if not tip, the Warthog. Go down through the tunnel, around the triangular ramp, and charge up the ramp behind it. Watch out for the carrier forms.
At the 1.5 km mark there is another large tunnel with a large drop followed by a large climb that takes you to the next section.
The next part features Flood and Sentinels fighting. Swerve to either direction to avoid them, and proceed through the left or right corridors at the sides. Then, go through an S-bend corridor, where there are a few ramps, Sentinels, and many infection forms. Taking the shortcut in the wall is only recommended if you are driving along the opposite wall at the time since the turning circle of the Warthog is fairly large.
The next section can either be done through the center, or along the sides, both methods work. After this, the fourth room features a tunnel immediately followed by a ramp. Taking the ramp will often cause a fall, forcing you to either sidestep and drive around, or swerve between the pillars. After this room, Cortana will implore Echo 419 to extract.
One final ramp, through a room and a doorway, and the "extraction point" is reached.
If you want to watch, go ahead, it'll give you a checkpoint if knowledge of the second part of the run is too shaky. Otherwise continue. You have a little leeway (10 seconds, perhaps) as past a certain point, the audio will be cut off and the timer will start regardless.
Then there is a drop down, but instead of a climb back up as normal, there is a pillar. Avoid it and drive on the left or right over some grates.
There is a second unclimbable drop here, and an S-bend hallway. If taking the shortcut, you can get out, make a right, and find the Thirsty Grunt.
Make a right after the shortcut (in case the Thirsty Grunt made you forget) and continue down. After a smooth stretch, up comes the ravine. Go at top speed, but if you just go forward the whole time, on higher difficulties you will die from fall damage. Here are alternative ways:
1. Ease up on the acceleration once you are in the air, this will stop you from tipping. 2. Go out of the side, land on the wall, and grenade the Warthog back into the tunnel. 3. Same as 2, but for safety, bail out about 10 feet in the air.
There is one more drop, another corridor, and a final tunnel into which you drop. Get out as some crates block your way and leave the Warthog to its death on the Autumn. Alternatively you can double plasma grenade the Warthog out and continue (note it would be a good idea to shoot a rocket at the gunner about 30 meters up on the left wall).
Run through the flood, or if you moved the Warthog down, go up the ramp, back to the crate area, and up the ramp. Jump there, and the final cutscene should trigger.