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The majority of the vaults found throughout the Fallout series were used to perform social and scientific experiments on the populations taking refuge within. Some of these studies were relatively tame, if not altruistic in nature. Others, however, ranged from incredibly bizarre to outright cruel. To outline the lengths that Vault-Tec went to in producing these experiments, here are the cruelest and most disturbing experiments that Vault-Tec ever cooked up for Project Safehouse.

Updated January 23, 2022, by Tom Bowen: The Fallout series is best known for two things. The first — which seems to be an all too common complaint when it comes to Bethesda games in general — is that they can often be pretty buggy; especially at launch. The second is a little more positive, however, and that is the series’ fantastically well fleshed-out world. The attention to detail that goes into making a mainline Fallout game is incredibly impressive, especially when it comes to the series’ rich lore. This is particularly evident when it comes to the franchise’s many vaults, the majority of which were used to conduct unthinkable and unethical experiments on their inhabitants. All but a handful of the experiments could be described as “bad,” but some of them really were downright despicable.

12 Vault 87

Vault 87 served as a research facility for forced evolutionary viruses, with all of its residents being used as test subjects. After being exposed to one particularly nasty virus upon their arrival, they were then monitored by scientists who had been tasked with observing and recording all of the subsequent changes that came about as a result of the testing. The results were — to put it bluntly — rather terrifying.

Within two weeks of their exposure, many of the vault’s inhabitants were dead. They were arguably the lucky ones, however, as those who did survive were transformed into the Super Mutants and Centaurs that players would later encounter while exploring the Capital Wasteland. For as shocking as these experiments were though, they are just the tip of the iceberg.

11 Vault 112

Another of Fallout 3’s vaults, Vault 112 sounds like something straight out of The Matrix. Residents were placed into a state of suspended animation and hooked up to a special virtual reality simulator. Where it differs from the iconic sci-fi series is that test subjects were fully aware of the simulation. Had they known all of the details though, they probably wouldn’t have gone along with it willingly.

Subjects were originally told that the simulation would provide them with a perfect life, but it ended up being more like a VR horror game instead. This is because the vault’s Overseer, Doctor Stanislaus Braun, physically and psychologically tortured the residents using the technology; even getting the Lone Wanderer to help him do so at one point. Shockingly, Braun had previously been one of humanity’s greatest minds, but, as the old saying goes: absolute power corrupts absolutely.

10 Vault 27

Vault 27 actually has yet to appear in any of the actual Fallout titles, only bearing a mention in Chris Avellone’s Fallout Bible, a collection of documents providing a wealth of information on the Fallout universe. Although these documents are no longer reliable as “official” Fallout canon, they still provide a lot of interesting information and insight into the Fallout world.

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The experiment that was attached to Vault 27 is a relatively straightforward one; it was purposefully overcrowded by two times its maximum capacity. It isn’t difficult to imagine the immediate impact of such drastic overpopulation, but, suffice it to say the specifics of the results are uncomfortable to visualize.

9 Vault 19

This vault can be explored during the events of Fallout: New Vegas, where it has since been taken over by the Powder Gangers. But, long before they arrived, its original purpose was to test the impact of subliminal messaging on its inhabitants.

Upon arrival, the residents were segregated into two groups and assigned one of two colors: blue, or red. Afterward, the vault exposed them to various stimuli that were intended to provoke feelings of paranoia and distrust. Terminal entries within the vault indicated that these subliminal messages were very effective and that the mutual distrust between its divided population was rapidly approaching a violent climax.

8 Vault 12

In what is perhaps Vault-Tec’s most straightforwardly dishonest experiment, Vault 12 was designed with a purposefully faulty vault door that would not seal properly, allowing radiation to seep into it so that its impact on the human body could be studied.

This would naturally result in the majority of the vault’s population becoming ghouls. They would eventually emerge to found the ghoul haven of Necropolis, which the Vault Dweller can explore over the course of the original Fallout title.

7 Vault 75

The experiment attached to Vault 75 is a solid contender for the absolute cruelest experiment ever carried out by Vault-Tec. Situated beneath Malden Middle School in the Commonwealth of Fallout 4, its stated purpose was to protect the school’s students and their families in the event of a nuclear attack.

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Upon entry, the students’ parents were separated from their children and were summarily executed by the security staff under the pretense that they were undergoing “orientation.” The children were then subjected to rigorous physical and mental conditioning. Those that did not achieve satisfactory results were disposed of once they reached the age of eighteen, and those that did were “harvested” for their superior genes.

6 Vault 22

The experimentation carried out in Vault 22 wasn’t necessarily disturbing at its core. It was designed to sustain life purely by way of “green” living, keeping its inhabitants alive by virtue of the plant life that was grown and cared for within. The results, however, are where things start to get dark.

A certain, specialized fungus was used to keep pests from ruining their crops. Unbeknownst to them, however, were the mutagenic properties of the fungus. Once the spores took root in human hosts, they would gradually transform them into spore carriers, deadly and aggressively cannibalistic mutants that have claimed many lives since.

5 Vault 34

This vault is perhaps most famously remembered as the ancestral home of the Boomers faction in Fallout: New Vegas, where they resided before establishing their community at the Nellis Air Force base. It turns out that their affinity for weaponry has some deep and disturbing roots there.

Vault 34 was purposefully designed with cramped living conditions as well as an absurdly overstocked armory full of weapons and ammunition. The cramped vault would soon become overpopulated, and the residents would continuously request access to the armory in order to protect themselves, which the Overseer would deny. This would eventually result in violent rioting.

4 Vault 106

Vault 106 was designed to simply begin pumping psychoactive drugs into its air filtration system a mere ten days after the door had sealed itself shut. Perfectly aware of the vault’s purpose, the Overseer directed security personnel to dismiss any complaints resulting from this.

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The Lone Wanderer can explore this vault during Fallout 3and will quickly come to realize that these drugs are still being filtered into the vault when they begin experiencing vivid and violent hallucinations. The few survivors left inside have been driven completely insane by consistent exposure to them and will attack anyone on sight.

3 Vault 81

The conclusion of Vault 81’s experimentation is a true rarity, as the Overseer realized the inhumanity of its purpose and put an end to it before any lasting harm came to its general population. In fact, the Sole Survivor can explore Vault 81 in Fallout 4, meeting its population of relatively sane and decent inhabitants.

Originally, the vault’s purpose was to expose the population to an array of deadly diseases and illnesses, while a science team operated from a secret locale to develop and test various cures on the subjects without their knowledge.

2 Vault 95

Vault 95’s stated mission almost seems altruistic in nature. It was to serve as a rehabilitation clinic for chem addicts, allowing them to overcome their various addictions, even as the outside world collapsed under a volley of nuclear missiles. However, its true purpose was much less than kind.

Although its detox program was a great success, a massive stash of chems and alcohol was hidden inside the vault, and a planted resident would “unearth” this cache after five years’ time. Predictably, the staged discovery of this cache precipitated the vault’s program unraveling entirely, and its population plunged into chem-fueled anarchy.

1 Vault 11

Of all the cruel experiments that Vault-Tec executed on unsuspecting victims, the one taking place at Vault 11 has to be the worst. Vault 11’s inhabitants were instructed to select one of their own as a human sacrifice each year. If they refused, they were told that the vault would shut off its life support systems, and the entire population would die.

In reality, should the vault’s residents refuse to sacrifice someone, the vault would provide an automated message congratulating them as “a shining example of humanity.” By the time that they couldn’t bear to sacrifice anyone else and bravely refused, its population had been whittled down to a mere five people. Unable to cope with their guilt after this brutal realization, four of those five people elected to commit suicide.

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