Teresa Lipan: "Gabe, the snipers have been cleared. Wait for our troops to arrive."
Gabe Logan: "Negative. Touchstone is in there somewhere and I'm not going to let him get away. Logan out!"
The difficulty will spike in this particular mission. It's very long depending on your objective, and has seemingly infinite enemies at certain points. You also get the most number of different kinds of weapons to pick up. You'll want to have your thermal goggles on pretty much the whole time. The key here is to use specific paths that prevent enemy spawns from occurring.
When you start turn immediately to your left and use the MB-150 (6mm) to take out the sniper on the roof of the building in the distance. Although any weapon will work you'll need a scope and the MB-150's precision will be a lifesaver; go for a headshot, and make it quick.
The 2nd sniper will be to your right, on the roof above you. Walk back until you can see him, preferably his legs. If you use something explosive (the exploding dart is perfect) he'll most often get knocked off the roof and you can pick up his weapon - it's a BFG rifle (sweet!).
Once you go down the ladder you'll see an infinite ammo box to your right. If you climb up the quarter-dome "skylight" thing you find a hidden crevice with a box containing a full-auto shotgun in it. If you pick up one of these shotguns later this box will refill the ammo for it. To your right you'll see a gate where you can blow the lock off. You're welcome to take this path but it's much easier to save it for a bit.
Proceed around the building & snap to the last wall on your right before turning. Two guys will come out; the one on the left will be harder to kill. Past them the path turns right again and there's a set of stairs going down. There is a sniper on a tall roof way off to the left. Again use the MB-150 and take him out first. Men wearing full armor will run around the open area at the bottom of the stairs. Run back and forth along the walkway, where you peek out then are covered by the building. Take out the men as they get to the left; use the most powerful gun you have (like that BFG) and aim for chest shots instead of headshots. Leg shots will slow them down and kill in 2 hits - also a decent way to go. Hit pause and go to inventory to look up info about your weapon - if it mentions something about being effective in a "locked bolt" position for semi-auto, then set it for single shot instead of full auto or 3-round burst. Shotguns will be ineffective, because of the distance required.
Beware, as the last sniper has been up on the roof to your right the whole time. You'll be in his sights if you go into the area where the men in armor just were, or the edge of the landing where you are. Again, if you use an exploding dart you can sometimes knock him off the edge of the building and take his BFG. Stay on the landing and look for a sleeve.
Once you enter this open space at the base of the stairs you'll see a box with a flak jacket. Don't grab it yet; you can take flak jackets from the bodies you've killed. In front of you is a stack of crates with a ledge above it; men will appear on this ledge. The best way to kill all or most of them is by blowing up the barrel. An exploding dart will do the trick, although it's better to just shoot the barrel (you get more environment kills by shooting it). Run around on the ground in front of the crates to grab their attention and make them come forward, so that they stand closest to the barrels.
Climb the crates to get to this ledge. There's a medkit on the column on the right, and a box with grenades. Take the grenades. Men will appear below you. Kill them as you please (those grenades will come in handy). They're wearing full armor. Exploding darts work well too, since they tend to move around and then regroup.
Getting to the gate where you'd climb down the crates will trigger 2 more to appear on the landing you came from. Kill them as you please. An exploding dart (with thermals on) is an easy way.
If you're still on the ledge you can walk farther down. There is a gate where you have to shoot the lock off. Do so and climb down onto the skylight thing. That orange body has hidden evidence. Then go back the way you came to the gate on the ledge where the barrel was. Climb down the crates.
When you get back to the landing, you'll have another guy appear in full armor at the other end of this walkway. Kill him. He carries a .357 sniper pistol - it's not silent but it's powerful and has a scope.
When you get to the landing where he was (you're headed back to your starting point) there will be many men. All will be wearing full armor except for the one on the top. When they are dead, head for this area. Men will appear behind you. You can head back up the ladder to your starting position for a good vantage point. If you have any guns you really like and they're low on ammo, and not the kind that people drop then remember the ammo box. The guy who appeared in your starting point drops an AU-300 H-Bar; it's a great weapon if you didn't manage to snag a BFG.
Now's the time to open that gate and take care of the portion of the mission on the lower level. Once you've opened the gate and climbed onto the "roof" turn to face the gate - now head to your right (away from the rest of the facility). In the corner is a nook you can climb into for some hidden evidence. There is a ladder you can climb down, but hold off on that.
Go along this "roof" until it curves right. Stop. Peer down below and you'll see where you've triggered men to come out. You have a great vantage point to sniper them out. Beware of the one that rushes past and gets below you and out of view (told you to keep those thermal goggles on!).
Now you can go to the ladder and go down. When you get to the bottom there will be a man waiting for you and another on the way. Once they're dead your path is clear for a bit, since the men that you would have normally triggered are dead. Those two guys are the easiest (relatively) to push off the edge if you're looking for those environmental kills. It's not easy.
When you get to the point where you sniped them off and walk forward you'll see a ladder on your right. Up the ladder and to the right is a dead body with a keycard and flak jacket. If you climb over a pipe and go all the way down you'll find more hidden evidence. It's best to ignore this ladder for a while. When you get about even with it 2 more men in full armor will come out. They're carrying full-auto shotguns and can kill you quickly especially as you get closer.
When you get to the point where they were (the walkway turns right) there will be more men appear wearing full armor from the left. Proceed down the path and deal with waves of enemies until you get to the end.
If you took the keycard off the dead body, you'll trigger a scene. A bad guy is holding two civilians hostage. Use a gun with a scope to get a headshot when he pokes his head to the left of the hostage he's holding. You have the option of ending the mission there by simply going through the door.
When you get to this area where the keycard/door is, you've automatically triggered the lower levels to reset with enemies. If you are playing for any specific mission objective you'll likely need to go back through the lower levels and clear them out. This is why you should save getting the keycard for later. If you're on Story Mode, make sure to hit up that ammo box last thing. Use the guns that enemies drop for your primary refills first, and use the box to refill the special weapons (like your 6mm darts).
This walkthrough is significantly more tactical than the first and assumes you're just completing the mission, without hidden evidence or power weapons.
Kill the first sniper to your west, then quickly take down the east guy. Slide down the ladder to your north, then climb the right platform to the dome and get the shotgun inside (if you so desire). Drop back down, and use a shot to unlock the gate opposite the dome. Slowly proceed forward on this platform, being careful not to fall down.
A wave of enemies will assault you from down below. Use your elevated position to your advantage and snipe them with the MB-150. Continue killing them and then advance forward, following this like glue. You will eventually come to a point where you must shimmy to the next platform, so make sure all the enemies are dead before doing so.
Assuming you followed this closely, you'll come to a dead body with a keycard and flak jacket. Get the former and, if you require armour, the latter. This will trigger another group of enemies that spawn below you. Sift them, and then carry on following this platform. Shimmy across until you come to yet another solid platform and climb up. The third sniper can be pegged from this position.
Return to the area with the corpse, and slide down the ladder to the catwalk. Take down the enemies (if they spawn), and follow this to the main compound. Neutralise any enemies that threaten you, and watch out for the last marksman. Shoot him and then collect weapons or ammunition as you wish.
You can now head to the door where the hostage taker threaten to kill the civilians. Either try to snipe the soldier's head or use a taser on the innocent. Watch out, for the OPFOR (Opposing Force) has a shotgun. I strongly suggest stunning the civilian and IMMEDIATELY start sprinting away from the innocents to lead the enemy away from him. You can then use a rapid fire weapon to drain his health. When you're done, return to the door and use the keycard on it.
- At the start, kill the two snipers and go down the ladder just in front. Get the shotgun inside the crate above you if you wish, then follow this path, taking down whoever stops you. You will eventually be able to see another pair of marksmen, so kill them. Climb up the crates on the far side of this area and keep going. At the end is a gate where you shoot the lock off. Go through and hop down onto the rounded "skylight". Examine the body for evidence.
- From the starting point, head down the ladder. Shoot the lock off the gate to your left and go through. Land on the "rooftop" and turn to your left. Go all the way down and look into a crevice on the left.
- Starting from the area listed above, go down the ladder onto the lower levels. The walkway will turn right, then left, then right again. You'll see a ladder on your right. Go to the top, where the body in orange (with the keycard & flak jacket) is. Climb over the pipe near the top of the stairs and keep walking. Where this passage ends you'll find another piece of evidence.