Find the location of Vault 14. 500xp
Marcus can show you the way if you ask him why he's not wearing armor. Use the separate computer in the military base (on the second floor) to find the location of Vault 14. After talking to Marcus, you'll have a random encounter: two dead super mutants near the railroad tracks with the Vault 14 access key.
The southwest tent contains a map of the region, which reveals the coordinates of San Francisco; the others contain weapons and useful items. To enter the base, you need to blow up the entrance as follows: examine the mine cart at the collapsed entrance, insert a nearby metal pole, attach explosives to it, and push the cart. The explosion clears the way (+5000 experience).
Level 1
The level is full of rats and Enclave soldier corpses, from which you can loot items and a holodisk, which will tell you about the level's events. In the southwest corner, there's a faulty generator that needs to be repaired to get the elevator working (+1500 experience). The elevator leads to levels 2 and 3.
In the northeast of the level stands a harmless super mutant who doesn't attack unless spoken to. He can be used to test the NCR doctor's serum. If you continue, you'll find a staircase leading down. We enter the cave, eliminating all the mole rats along the way. We proceed to the next cave, eliminating all the creatures, including a rhinoceros rat. We see a descent downwards, and a working monitor nearby. Using science, we determine the cause of the breakdown (+35 exp) and repair it (+35 exp). Next, we head to the eastern part of the location, where there's a door. Using the Lockpicking skill, we learn that we shouldn't lockpick it, otherwise the base will collapse. Next to the door is a terminal with a monitor. We learn that the terminal is locked behind an iron box. We lockpick it (requires a skill of at least 135%), and then learn that the terminal is broken. We repair it, but the door still can't be opened; we need a code. Hover your mouse over the door using the binoculars to find the code 2077. Open the door. I wouldn't recommend going down without a gas mask.
Level 2
The location contains three rooms with super mutants armed with flamethrowers, power fists, and one plasma rifle. When a group of mutants is attacked, the other groups will also attack.
The crates and corpses are full of tasty treats, weapons, ammo, and power armor. To the northeast is a working computer that contains the coordinates to Vault 14 (+500 experience).
Level 3
There are also plenty of mutants, armed with flamethrowers and power fists, plus one plasma rifle and one laser rifle each. Crates and corpses contain many tasty items, including a Green Memory Module. To the southeast is an elevator to the fourth level.
Level 4
In the north stands a super mutant, Melchior, with supernatural powers: he can summon monsters. If you're low on strength, you should defeat Melchior as quickly as possible. Killing all the monsters he summons will net you over 14,000 experience.
You can get a laser rifle and a Gauss pistol from the boxes and from the corpse of a mutant.
Source: falloutmods.fandom.com.