*NOTE: I'll remind you twice, and sorry if this first is any sort of spoiler, but to handle the creepers it is best to use slo-mo. By not using it you are making them a ton more difficult, and they take out half your armor with just a few swipes.*
If you don't know, the spazzing out of your interface is a good sign you're in what I call, "creep out at any moment" mood. Go up the ladder, and if you want a chill turn around at the top and look through the door window, and of course moving out of this room resolves it.
In the room with blood is an intel by the body, along with some ammo and a med pack at the back. Go down the hall there is a hard-to-see creep on the other side of the glass, and when... someone busts through a door be ready to mash the melee button to shake him or her off you; there is nothing through the door. If you move up and look down from the next window you'll see troops moving through an area you've just been. Go through the control room nearby, in which there is nothing of interest, and you get a quick jolt and you're sort of out of it.
Go left and another left to see through a window at a very interesting sight. Come back and go down the steps for ammo and a proximity mine. Go out the door and over the rocks in your path. Take the steps down and before you press the switch you should know that there are three cells and you'll open all three, but one has a creeper thing, the bloody cell. Pressing the switch opens the cells but locks you in the room. So go back up the steps and when you go out for the doorway jump out the window directly to your right.
Equip shotgun and he's not in the bloody cell, he's in the third one; I know, that ruins the scare, but it's a fine line between scares and combat. Move along to get into that interesting room, and when in front of the subject shoot him as he stirs and then be ready for another creeper to your right. Proceed around to the upper part and another one enters the room from above. And as you go up the stairs another will appear to the right and land at the top of the steps.
Go through the door and get the med pack and intel. Go around the corner to run into one through the window, and then another when you move up. When you move up to the room ahead two will be to your left near the armor, so wait until you back up down the hall and kill them, as well as a fifth one when you move near the stairs (he hops on the rail), and then pick up the armor. Go down the steps.
Save the armor here unless you need, because there are two more creepers just through the opening, one as soon as you peek out and one when you step further out, both around the forklift. Move down to the bombs where one emerges from the floor and then a second by the rail to your left. On the other side is a panel with a ton of meds that will fall, so let it, and then pick up the other three if you need any health.
*NOTE: Another reminder, use slo-mo! Makes them a ton easier.*
To the right is your opening, and when you run past the crack in the pipe with the steam coming out, run to the ladder and turn to take out the creeper. Go up and through the door for an intel and armor. But save the armor and after you read the intel be ready for three creepers to run at you, so go slo-mo and back up out the door and to the ladder; probably out of shells by now, so use the SMG. After the fight there are some shells, and then just follow the path to the elevator and take it up. The creeper that hops on above you is of no peril to you.
*NOTE: The movie on the screen and the creeper are in a room to up and to the right of the entrance.*
At the top and to the right are gates to open for ammo for the Assault Rifle, which I will call ASP. Get em and go into the arena. Watch the movie and then take cover just to the right, in the half-wall V near where you entered. When the soldiers pop up just go slo-mo, blast the first one to the left, then run to the other two and blast them with you shotgun. The second wave is tougher because they pop up in not so easy to spot locations, but most come from the left, so get over there and toss a few frags as you blast a few and go melee when you can. The third wave is more in the open, so you can have frags waiting for them, and at some point you may have to switch to your ASP. If you need to hit the car in the middle during this wave, fine, otherwise get the armor and health before the fourth wave. The fourth wave is in the open too, but a certain someone will arrive and cut the game short.
Not sure when you got them, perhaps now, but there are shock grenades to be found here. As you collect ammo, just don't fall down the opening hole to the right because that is the way out, so after you run around this area hop in there. You land near where you started.
Hop down and go right for ASP ammo, then have your shotgun out and go left to fight about five enemies, so use slo-mo. Pick up an Automatic Shotgun by swapping out your old one. Use it on the two down the path. Go up the ladder and be ready for three more in the next room. Pick up the ammo and armor and follow the path to an area with clusters of pods. It's best to go left, away
from the pods and just slow-mo, toss frags to the middle because about eight will emerge. Kill them, and on the side you can hop down for a med back, and if you stand back to blow up some bombs by a vent you get two mines.
Go back up and lift the box to get through the door, and past the save point you will hear a fight between the soldiers and Replicas, or however you want to phrase it - it's the two kinds of bad guys. Go through the door and the pro tip here is to let the Replicas mess with the one soldier as you go up the ladder, save the armor unless you need, pick up the intel, and follow the cat-walk to flank the Replicas with a nice slo-mo grenade, but don't forget about the soldier behind the glass; and some of the glass is bullet-proof. Pick up all the ammo after, go get that armor if you saved it, and move up the steps.
Follow the creeper down the pipe and kill him behind the stairs. Go up and get ready for one big fight. Have you rifle and incendiary grenades ready. Go out slo-mo and toss a grenade to the two enemies away while you blast the one to the left by the steps, then go right and kill the two on the side. Now quickly move up the room and toss a flame and a normal frag to the upper left corner of this room, by some stairs, where all the Replicas are spawning. The flame should get any already there and if you wait to toss the frag you should take out the rest that are present since there is a bomb there also; and if you see the bomb after the frag then shoot it yourself. Then just get under, go into slo-mo, and kill the rest that pour out.
Tons of stuff to collect. You can hop onto the truck bed, there is a lock to shoot up the small steps for armor and ammo, and then take the ladder to have a full ASP clip. Go up the steps and follow the path to one more big open area. Kill anyone you see from above, then drop down by the broken ladder and into the nearby door for supplies and an intel.
Now there are two enemies in here to start, both should be hiding, so find them first. Go to the far left side of the lift and press the panel, then fall back to cover from the Replicas that emerge from the nearby pods. There are two more groups of them, by the two other valves, so go around this room, try not to touch any armor until after you've killed them all.
Before you start turning valves I strongly advise you to save the one near the lift for last. Get out your shock grenades and you'll notice there are plenty by all the supplies dotting the room. Turn the valve in the far corner, and then the one near it; again, not the one on the ground by the lift. Turning two will trigger the mech to emerge.
Now killing him is optional, and I would advise against it since there is really no need at all. All you do is lead him to the first supplies behind the lift, stun him, then run to the valve, turn it, use the lift panel, hide behind some cover, and wave to him goodbye.
*NOTE: If there is any reason to kill him, please let me know. I got the trophy and didn't kill him, and there are no others that specify him as a target.*
*NOTE: I have read that you need to stun it, keep stunning it, tossing cooked frags, and I guess get in a few shotgun blasts is the way to beat the darn thing. I would guess it's shield will trigger after a hit, so perhaps you have one frag then the shield pops up, or one bullet and then the shield pops up. I'm not sure. All I know is I'm on the next level.*