On the Vault-Tec computer in the Citadel, the premise of the experiment was explained to study conflict for leadership and power in a vault. The first overseer, Brody Jones, was known to have a genetic predisposition for a rare form of cancer that was expected to kill him within 40 months of the experiment's inception, and positions of authority in the vault went unassigned and discretion was given to the Overseer. The main power supply was also scheduled to malfunction after 240 months (20 years while the vault was planned to be sealed for 38), and the back-up power supply was intentionally insufficient to meet the vault's needs. On top of all this, the vault was given three times the normal armory stock and no entertainment recordings.
There is a holodisk found in the cloning lab (A on the map) (located near a body near one of the examination tables, this room also has a very easy locked safe in it as well as Gary 12 and 36) that hints about the fate of Vault 108. Every time Gary was cloned, it immediately became hostile to non-clones, with each one becoming more violent. After the 53rd was no different, the staff began to wonder what to do with all of the clones, as the vault's observation rooms were becoming full. The other entry in the holodisk says that Gary 54 was the same way, having injured Doctor Peterson during an examination.
The entry also states that they will be destroying some of the clones, to make room for "many more tests". What happened next is not clear. What is clear is that the only survivors are the Gary clones.
The entrance area is occupied by a colony of mole rats. The living quarters and cloning lab are inhabited by a dozen clones named Gary, all of which are hostile. With the exception of Gary 1, 25, and 32, all other clones initially are unarmed, with knives or lead pipes. Their AI, however, may direct them to pick up stronger weapons that may be nearby.
- A Stealth Boy is between two terminals in the northwest corner of the room with the door to the living quarters.
- A Nuka-Cola Quantum is behind shipping crates in the narrow room east of the door to the cloning labs.
- A Tumblers Today is on the same stepladder that the Nuka-Cola Quantum is sitting on. It may have fallen underneath the stepladder, or may do so when you pick up the Nuka-Cola Quantum, so pick it up first. If fallen, it can't be picked up with perspective tricks or fancy footwork but it can be taken. See the bugs section of the Tumblers Today page for how it's done.
There is a Pugilism Illustrated in the living quarters, on the counter in the cafeteria (the northernmost room on the local map).
- Bobblehead - Charisma - Located in the vault cloning lab on a table in the observation room (located in the center of the map), which looks into the main operating room. The bobblehead can be found on a table beside a microscope.
- In the same room as the bobblehead, is a Lying, Congressional Style.
- The holodisk in the cloning lab ("Cloning log") that slightly explains the events of Vault 108 is in the room where there's a black cube safe that can be lockpicked. Look for a skeleton on the floor next to an examination table; the holodisk is close by.
- It is possible to encounter a number of radscorpions, deathclaws, sentry bots, an Enclave camp (after The Waters of Life quest), and super mutant overlords (Broken Steel required) outside the vault's entrance at higher levels when fast traveling.
- In the Outcast outpost where the Anchorage simulation is located, there is the dead body of Gary 23. Presumably he left Vault 108, was captured by Brotherhood of Steel Outcasts at some point and taken to the outpost. It appears the outcasts tried to convince him to enter the simulation as he had a Pip-Boy 3000, the correct interface device, but soon discovered that the only word he said was "Gary" and he was hostile to all non-clones. They grew impatient with him, and he was beaten to death with some brass knuckles which can be found close by. The Outcasts then sawed off his arm in a futile attempt to remove his computer. His body has been unceremoniously dumped in a corner.
- A cut audio holotape would suggest that Gary 23's arm was sawed off by the Outcasts while he was still alive, without the beating.
- This vault is likely the most deteriorated vault located in the Capital Wasteland. The inside has completely rusted away over the years, the vault jumpsuits are the dirtiest of all, and it appears as if the only major loot in the vault is the Vault-Tec bobblehead located in the cloning lab.
- Because of this deterioration, Vault 108 is the only vault in the Capital Wasteland without a single working terminal.
- Just like Vault 87, Vault 108 does not contain a working vault door control pad. The vault door is opened directly at the main door by selecting the option to open it.
- The overseer's office is inaccessible, and also has a different window than other vaults in the region, as it is rectangular, instead of round.
- Also, the reactor area is completely inaccessible, due to a blockage of debris in the reactor entrance, located in the cafeteria.
- Although Vault-Tec records state that Vault 108 had triple the normal armory stock, no trace of this armory can be found when the Lone Wanderer arrives in 2277.
- In the living quarters dining area there are three radroaches: a normal sized one, one that is slightly smaller (the same size as the ones kept by Gallo) and one smaller still, making it the smallest found in the game.
- If aimed at while in sneak mode the Gary clones will still make the usual "Be careful" comment, despite their vocabulary supposedly consisting of only the word 'Gary'. Also, when killing Gary clones, they can also be heard saying "No!"
Vault 108 appears only in Fallout 3.
- Playstation 3 Xbox 360 When using a railway rifle, Gary's head may come off and float in mid air with the spike through his face. [verified]
- Xbox 360 In the cafeteria, there is a blocked door that appears to lead to the vault reactor room. However, if you manage to clip through the debris and activate the door, you will be in a hallway that doesn't lead anywhere.[verification needed]