If you’ve been playing Fallout 4 non-stop over the past few weeks, odds are you’ve heard of a little corporation called Vault-Tec. They designed and built all of the nuclear fallout shelters throughout the post-apocalyptic world of the game and its predecessors.

Originally Vault-Tec served as a contractor for the United States government, working on top-secret military projects for the Pentagon and advanced technologies for the country. As time went on, the corporation became so involved with the the government that many considered it a department of the U.S. government itself — so when the Great War of 2077 loomed on the horizon, Vault-Tec was brought in to help with Project Safehouse; a plan to build vaults to protect the U.S. when the nuclear bombs fell.

The United States government knew that they couldn’t save everyone — with a population of almost 400 million by 2077, they need 400,000 or more vaults to protect everyone. Since each vault cost around $400 billion or more, they elected to follow a more sinister plan to preserve the country.

Known officially as the Societal Preservation Program, Vault-Tec and the U.S. government would work together to build 122 vaults and pre-select groups of the American population who would inhabit them. Then, after the bombs fell, they would observe how these groups reacted to the stresses of isolation and how successfully they would re-colonize once the vaults were opened. In addition to this observation, many vaults were specifically designed to conduct experiments on live human test subjects.

These experiments were actually the work of the Enclave, a shadow organization of federal officials and corporate executives that used Vault-Tec to setup these horrible experiments — which were supposed to help them prepare for building back up humanity or moving to another planet. These experiments ranged from the creation of genetically modified super soldiers to intended radiation exposure, without any worry for how they affected the Americans isolated inside.

But which experiments were the worst of this in-game programming? Well, that’s something for you to decide. Here’s some of the worst experiments that would be carried out in the Fallout universe.

Vault 11 - Fallout: New Vegas

Vault 11 was considered a social experiment. In this experiment, those living within the vault were told that they had to sacrifice one of their own every year. If they refused to do so, everyone would be killed within the vault. So as the years passed by, the inhabitants killed one of their own until they refused to do it anymore; with only five inhabitants remaining. Upon refusing to kill another one of their own, an automated message played for them calling them “a shining example to humanity,” and stating that nobody would be killed. I suppose it’s just a shame they didn’t attempt to break the rules earlier as the government had hoped they would.

Vault 12 - Fallout

Located under the city of Bakersfield, California; Vault 12 was home to a thousand people before the bombs fell. However, the door was intentionally designed to malfunction and remain open; which allowed toxic clouds of radioactive waste to leak into the Vault. This resulted in the ‘ghoulification’ of those residing in Vault 12, causing their hair and skin to fall off and mutate due to radiation exposure. These residents would eventually go on to found Necropolis, a city made up entirely of ghouls.

Vault 75 - Fallout 4

Vault 75 was placed underneath Malden Middle School in the Commonwealth as a public vault for the children to retreat to in the event of nuclear war. So, when the Great War began in 2077, children and their families naturally retreated into the vault. Upon entry, the children were separated from their parents and escorted into a different room while Vault-Tec security killed their parents. The purpose behind this experiment was to enhance the gene pool with select residents in order to create a stronger, more intelligent population with which humanity could re-populate with once the vault was opened. Due to the nature of the experiment, the surviving children were tested mentally and physically up until their 18th birthday; where their genes were harvested, they were killed, or they were recruited by the science team in charge of the experiments in the vault. This process would continue until rebellion among the population, which cleared out Vault 75 for your arrival in Fallout 4.

Vault 68 and Vault 69 - Fallout Bible

Mentioned in the Fallout Bible, Vault 68 and 69 were designed to test social and reproductive behavior. In order to do so, Vault 68 was populated with 999 men and 1 woman, while Vault 69 was populated with 999 women and one man. The results of the experiments are unknown.

Vault 92 - Fallout 3

The world’s best musicians were invited to come to Vault 92, which was promising to preserve musical talent during the Great War of 2077. However, the vault was actually designed to experiment with white noise generators that implanted subliminal messages into the minds of its population, hoping to create super soldiers that could be controlled through a form of hypnosis. This experiment ended up taking a turn for the worse though, as rage and aggression started to take over the residents. This resulted in more than half of the population becoming violently unstable and starting to slaughter the rest of the inhabitants, although some of the population escaped the vault during the chaos who had yet to be influenced by the experiment.

Photos via fallout.wikia.com, Bethesda Softworks