X18

With both keys in your possession, you can head into the secure lab underneath the buildings. Your goal? Find more documents for Barkeep. As you poke around in the first few rooms, you’ll find a door locked with a keypad. You need to find the code for the door.

The Monolith suit will serve you well for a long time to come.

Poke around in the immediate vicinity until you find a locker room a very short distance away, just to the northeast of the keycarded door. Opening up all of the lockers here will reveal a Monolith Suit, which, despite not being worth as much, offers more protection to some forms of damage than your stalker suit does. You’ll also find an Akm 74/2 rifle with an underslung grenade launcher, along with a couple of grenades. Sweet. The default button to switch on your grenade launcher is V. You won't find many grenades to use here, so keep that in mind.

This is a fairly small upper level of the lab, but a dangerous one. There are numerous hazy anomolies scattered around that will burst into flames when you pass through them. Occasionally you can avoid the flames by simply sprinting through the anomolies. Regardless, if you poke around long enough, you’ll find the body of the worker. His PDA will reveal to you that the code to the door is 1243.

Heading Down

Go to the door and open it. When you reach the bottom of the stairs, you’ll notice that more of the objects here will fly through the air at you, seemingly at random. Don’t worry about them, though, as they only cause light damage. Be more wary of the rapidly moving electrical anomalies in the area.

The pseudogiant is intimidating, but it'll die if you shoot it in the head, just like anything else.

If you head towards the green dot on your HUD after finding the second locked door, you’ll find that a Pseudogiant is blocking your path to the access code. You’ll feel it before you see it, as it shakes the floor when it walks and can slam its feet into the ground for an earthquake attack. Kill it by shooting it in the head, then find the dead scientist in the red suit to obtain the keycode for the door - 9524. The scientist should also have an IL 28 assault rifle on his person which you might want to keep, although ammo for it will currently be scarce. There should also be another rocket launcher on the ground nearby.

With the keycode in hand, return to the locked door and open it. Here’s where things get complicated. The, uh, entity that’s been throwing things at you this entire time is inside this room, even if you can’t see it. It will follow you with jets of flame and attempt to burn you, but you can avoid these if you stay mobile. There are some cabinets with goodies up the ramped exit to the main room; in the control room atop the little experimental area, you can find the documents that you’re looking for on a desk.

Escape!

Blast your way out of the base with your documents in tow.

Now that you’ve angered the entity here, it’ll hold the door shut and prevent you from leaving. It can be difficult to discern precisely what to do here, but what you need to do is find the entity and kill it. It can be seen floating around the room, a tiny bundle of orange sparkles, distinct from the jets of flame. Track it down, follow it around, and fill it with bullets. It might not look like you’re damaging it at first, but eventually it’ll explode, allowing you to leave the room.

When the cutscene ends, fight your way through the soldiers that come into the facility. Note that they carry the upgraded Obokan rifles, an upgrade to the Akm 74/2. Even if you’re still using the grenade launcher attachment, it’s probably worth making an upgrade here. You can right-click on the Akm to dismount the grenade launcher and affix it to another weapon, if you like.

Escape From Dark Valley

When you reach the exit to X18, the building will quickly be swarmed by soldiers. Don’t worry about fighting them, unless you want to; just sprint out of the front gates and hit the road. The only exit available to you at the moment is apparently the southern one, which will lead you back to the Cordon. You can return to Sid to pick up a side mission for a little cash.

Return To Barkeep

If you wish, you don’t need to speak to Sid, you can simply head north through the Garbage to the Bar area and return to the Barkeep. He’ll hand over a cool 10,000 cash for the documents, and refer you to another lab, named X16. Yay! Another fetch mission. The "Find the Family Rifle" mission from the guy named Hunter in the bar will overlap with this quest. When you reach the Wild Territory, keep in mind that the dot indicating the rifle's position is actually intended to be underground; you need to find a passage near the burning chopper to reach it.

Head northwest out of the Bar and into the Wild Territory at this point. As you do so, you’ll come under fire from snipers in the buildings to your west. You can either snipe them back, or simply run into the building underneath them and find the ladder leading up. The soldier near the ladder will have a new TRs 301 assault rifle, which is quite powerful, even if you don’t have enough ammo to use it yet. The snipers themselves will have older model rifles, but if you pick one up, you can detach the scope from it by right-clicking on it in your inventory and then attach it to another weapon.