Vault 71: A control vault that was originally intended to be opened 30 years after the bombs dropped but due to change in leadership it was changed so that the vault door is to remained sealed at all times so that the overseer can have total control over the vault dwellers. It was forced open in the year 2297 by the Enclave, who then slaughtered everyone within with only the player surviving the encounter.

Vault 117: A vault who's purpose was to produce enhanced super soldiers for the military out of young children. Out of 100 children within the Vault, only one had survived the enhancement process with the rest dying due to the negative reactions of their body to the chemicals the Vault Tec staff implanted into them. Fueled by rage and anger, the surviving child killed all of the staff responsible for the project and fled from the vault at the age of 11.

Vault 58: A vault who's purpose is to experiment on how claustrophobic people would react to being sealed within a confined area while exposing them to a gas that would enhance their paranoia. As the dwellers were exposed to the gas, their panic attacks were enhanced greatly with them running around the confined room banging on the walls and doors begging to be let out with high amount of desperation in their voice. Wanting to learn more on the affects, the staff poured in more gas within the chamber which in turn caused their panic attacks to be enhanced so high that it caused them to let out a loud scream of fear. Suddenly, much to the staffs suprise, all of the dwellers ran at the door and continuously ram at the door in the attempt to bring it down. The security attempted to prevent the door from collapsing while the staff turned off the gas in hope that it would cause them to stop but it was too late. The Vault dwellers rammed the door down and put up a fierce fight against the security and staff. Both have tried their best to contain the dwellers, but unfortunately for them they were overwhelmed and were killed by the crazed dwellers. After all of the staff were killed, the dwellers attempted to flee from the vault only to realize that the panel that controlled the vault door was destroyed by one of the staff members who managed to escape, trapping them in. Having no other option and becoming desperate, they committed suicide so that they can finally be free from their prison.

Vault 60: A vault who's purpose was to create a chemical weapon that would be used against any future communists after America was rebuilt from the ashes of the old world. Its said that the chemical weapon would cause the victims organs to melt, cause their skin to burn and to have them bleed from their eyes, ensuring a slow and painful death.

The Staff working on the weapon would select a handful of Vault residents and would expose them to the weapon to see if it would work as intended. At first, it would not work as intended and those who survived would be executed to avoid any suspicion. And if the test subjects had any close relatives/friends, they would be told that they were sent to the surface in search for supplies only to later tell them that they might not have made it. And they would continue to repeat this process in any future tests.

One day, during one of their tests, it seemed like they finally hit their mark. The subjects complained about their skin burning and feeling the pain in their organs. But the staff would later be surprised when they saw the subjects skins becoming rotten and bloated, turning into a sickly green color. The subjects would scream in pain and agony as it happened, begging the staff to either stop the pain or to kill them. Then, suddenly, a fleshy tentacle whip would be formed from their left arms and their heads would go limp, yet still standing. They soon became hostile and aggressive, attacking the staff and killing most of them, infecting them into becoming one of them. They would then spread across the vault, infecting everyone in their path either by biting them or hitting them with their tentacle whips. Only a few vault dwellers made it out of the vault alive and destroyed both of the controls to the vault door after sealing it tight, while one stayed behind to set the vault ablaze to kill all of the infected.

Now, the surviving infected roam the vault, waiting for the door to open to spread their infection.

Vault 78: A vault who's purpose was to create a super soldier that would be strong enough to take on a whole army. As the staff experimented on an unsuspecting Vault Dweller, the dweller changed both physically and mentally giving him a big, buff body and claws extruding from his hands while giving the dwellers face a more twisted and messed up look. It also made the dweller more hostile and blood thirsty, which led to the mutated dweller going on a massacre killing everyone inside. The mutated dweller now roams the halls of the vault alone, hunting down anyone that it laid eyes on.