Retrieve Parts Gain Access to Vault 15

Retrieve Parts/Gain Access to Vault 15 is a quest in Fallout 2.

Background
The New California Republic needs some pre-War computer parts from Vault 15, from where they originated. However, some squatters have moved into the area directly over the vault and set up a small shanty town. They reject any diplomatic talks with the NCR and deny them access to the vault. President Tandi is looking for someone who can get the computer parts for the NCR, and possibly negotiate terms for the vault and the town above it to join the New California Republic.

Walkthrough
If the Chosen One speaks with Deputy Karl (located in the Police Station in Downtown NCR) about work opportunities, he suggests getting an audience with President Tandi at the Hall of Congress, and that she is "looking for someone... resourceful." Tandi offers the Chosen One $500 for retrieving the needed computer parts from the ruins of Vault 15. One can also ask her about the history of Shady Sands and receive a NCR history holodisk from her.

Once arriving at Vault 15, one will find out that the squatters are not very friendly. Access to the vault can be gained by either completing the Rescue Chrissy quest and gaining their trust, or by simply killing their leader Zeke, and looting the key card from his body. If rescuing Chrissy, the Chose One will discover that the people living in the vault are actually a group of raiders, known as the New Khans, led by Darion.

Vault 15 itself is accessed through an elevator door in the side of the rock wall just left of the building Chrissy is being held in (the main entrance in Zeke's house cannot be used, as he explains). The computer parts will be on the third floor in the second room to the right, the one with the lockers lining the walls. At this point, the player can either return to Tandi for the reward, or kill kill Darion and persuade Zeke to let the vault be annexed by NCR for the good ending.

Now, all that is left to do is to see Gunther to get the reward. Once this quest is completed, no further interactions with Tandi are possible.