Bethesda's first foray into the nuclear wasteland was with Fallout 3, the RPG from 2008. The series had seen success as isometric, classic role playing games, but Bethesda brought the franchise into 3D, giving players a hybrid perspective with both first and third person. The series' V.A.T.S. combat system was reworked to provide players with a bullet time mechanic, where specific body parts of an enemy could be targeted in full 3D instead of just pointing at body parts. Although the game itself went through many design changes, Bethesda inherited the universe of Fallout, and used Fallout 3 to begin building the lore of the United States' east coast in post-nuclear 2277.
Fallout 3 takes place 200 years after the bombs of the Great War fell. At the beginning of the game, the player is a resident of Vault 101. Constructed by Vault-Tec, it is one of 122 vaults built across the country to ensure the continuity of the human race in the event of nuclear war. Unknown to those who enter the vaults, a large majority of them were designed as experiments, with the residents as test subjects. Vault 101 was never intended to open. The true nature of Vault 101 was to monitor the evolution of the Overseer position as the inhabitants remained isolated.
As far as Fallout Vault-Tec experiments go, Vault 101 is rather mild. The different eras of the Lone Wanderer's life that the player witnesses at the start of Fallout 3 show a functioning, albeit manipulated, community. After the Lone Wanderer's exodus, a revolution takes place challenging the authority of the Overseer with various outcomes dependent on player action. Other Vault-Tec experiments in the Capital Wasteland did not result in functioning societies, and, more often than not, the experiments conducted were so grim that the vault suffered a catastrophic failure.
Vault-Tec's Darkest Capital Wasteland Experiments - Vault 87
The main entrance to Vault 87 is nearly inaccessible due to lingering radiation presumed to be from a direct hit by a nuclear bomb before the events of Fallout 3 begin. The inside of the vault remained intact after the Great War however, where an experiment into the Forced Evolutionary Virus was conducted. In an attempt to genetically modify humans for survival in the nuclear wasteland, test subjects were exposed to the virus to disappointing results. The victims grew large and strong, became green-skinned, and lost most of their intelligence.
Vault 87 gave rise to the Capital Wasteland's super mutant population, who then terrorized humans by kidnapping them and bringing them to the vault to dip them in a vat of the virus. The super mutants of post-nuclear Washington DC are sterile, and subject humans to the transformation in order to continue the existence of their species.
Vault-Tec's Darkest Capital Wasteland Experiments - Vault 92
Vault 92 was advertised to its future residents in Fallout 3 as a means to preserve the musical talent of the human race. Renowned musicians were selected to enter the vault with a plethora of equipment available for the composition and recording of new works while awaiting the vault's opening. Unknown to the musicians living and working inside, the Vault-Tec Overseer initiated the White Noise Mind Suggestion Combat Experimentation project to see if the vault dwellers could be subliminally compelled to violence.
With the test subjects exposed to an increasing amount of white noise, it wasn't long before one resident began to feel its effects and violently murdered three other vault dwellers. It took 23 gunshots to subdue the test subject. The Overseer refused to terminate the experiment, and the violence escalated, with the white noise affecting multiple people. The increasing violence, combined with water damage to the vault itself, led to both the metaphorical and physical collapse of Vault 92. One of Fallout 3's rare weapons is given to the Lone Wanderer as a reward for retrieving a violin from the derelict vault.
Vault-Tec's Darkest Capital Wasteland Experiments - Vault 108
Vault 108 was a poorly conceived amalgamation of experiments by Vault-Tec, located not far east of where players can find Dogmeat in Fallout 3. It was initially envisioned to study the way in which leadership succession would happen, with the Overseer hand-picking all other prominent positions. Scientist deliberately chose a man with cancer to be the Overseer, estimating he would die about three years after the vault was sealed. In order to aid the potentially violent grabs for power, Vault 108 had an abundance of weaponry with no sources of entertainment for the inhabitants.
While awaiting the death of the Overseer, Vault-Tec scientists engaged in cloning experiments, wanting to see what would happen if one man, Gary, was cloned repeatedly. As it turned out, the Gary clones had a violent disposition toward n0n-clones, with each new Gary having stronger violent urges than the last. When the Lone Wanderer enters Vault 108 in Fallout 3, all they find is a pack of Garys - who can only speak their own shared name - that attacks on sight.
Vault-Tec's Darkest Capital Wasteland Experiments - Vault 112
Fallout 3's Vault 112 was designed to suspend its inhabitants in a virtual reality simulation for an unspecified length of time. The simulation would keep the inhabitants alive for an extended period, while also letting them live in an Edenic fantasy world - or at least, that was the idea. Instead, the Overseer was given complete control over the simulation, turning it into a source of sadistic entertainment.
The Overseer was Dr. Stanislaus Braun, notable for his invention of the Garden of Eden Creation Kit (G.E.C.K.), which the Lone Wanderer needs for the Purity Project. When the Lone Wanderer comes to Vault 112 looking for their father, who came to the vault to get information on the G.E.C.K., Braun has trapped the vault dwellers in the system's third simulation, Tranquility Lane, which has been running for years. Braun has been keeping the vault dwellers inside of the simulations as playthings - violently killing and resurrecting them repeatedly. The victims have presumably been trapped inside of the virtual reality pods for two centuries, being subject to the countless crimes of Braun ever since the bombs of the Great War fell.
If the depiction of nuclear annihilation wasn't pessimistic enough, the world of Fallout 3 is riddled with the aftermath of many crimes against humanity committed by Vault-Tec under the guise of scientific research. People who were lucky enough to escape the atomic blasts were subsequently turned into mutants, driven insane by subliminal messaging, killed by a posse of human-hating clones, or trapped inside the playhouse of a madman. While the Fallout 3's Capital Wasteland is hellish enough, being trapped in one of Vault-Tec's experiments is arguably more terrifying.