When a frightened child fears that monsters are lurking in the shadows of their bedroom they pull their covers over their head and cower, hoping that a layer of cloth will protect them from whatever unseen threats stalk the night. On October 23rd 2077 the nightmares became all too real when the Great War commenced. Blinding light ignited the sky, and people ducked and took cover as they had been taught, cowering under whatever they could, hoping that if they kept their eyes closed and remained still that the merciless flames would pass them by. They hid beneath desks at school, under cars on the street, and behind desks at work. Perhaps a few were in their beds when the flash appeared on the horizon and - perhaps they drew their blankets over their head like children, hoping that the searing pain was just a bad dream.
The ballyhooed tactic of Duck and Cover proved ineffective against armies that no longer cared about winning. Mutually self-assured destruction was the goal, and the American and Chinese exceeded it in spades. Hundreds of millions of people lost their lives within minutes, and billions more died over the days to come as radioactive fallout settled over entire continents. The fallout muddied the oceans, clouded the sky, and sunk deep into the soil.
Those who happened to be in the right place at the moment the bombs fell managed to survive. A well-timed spelunking vacation, a commute along the deepest subway tunnels, or the good fortune to live in a town in a place so remote that no one would ever think to bomb it. These "lucky" few formed the primitive tribal societies that struggled for survival in the years immediately following the war.
Hidden from those tribal bands were another group of survivors. Those who had been selected for Project Safehouse. One hundred thousand people fortunate enough to have been offered shelter inside impregnable survival shelters called Vaults, created by the Vault-tec corporation. The first vaults opened again a few years after the war and their inhabitants slowly spread throughout the wasteland. By now tales of the Vaults have spread from coast to coast, although not many people alive today have actually been inside one.
At the height of pre-war civilization, the government and a few powerful corporations knew that an apocalypse was brewing, so they used their finest technology to create vast subterranean bunkers that could withstand a nuclear blast, a meteor impact, global flooding or other likely disasters. The general public wasn't entirely convinced that their end was nigh, otherwise there would have been a greater demand for Vaults. When the war started there were only about a hundred of them, scattered across America, and many held less than the thousand people they were intended to hold.
Those who were smart enough or lucky enough to be inside one when the end came were protected from the devastation by airtight steel doors, thick walls of concrete, and over 200 feet of soil. The fine engineers at Vault-tec designed their bunkers to run independently for ten years and even more. Geo-thermal power, hydroponic farms for growing food, and a water purification system so efficient Vault residents could fool themselves into thinking they weren't drinking their own urine.
The designers made the Vaults as homey as possible despite the steel clad walls. The cafeterias were designed to look a little like roadside diners, and vault dwellers could close their eyes and imagine that they were eating a plate of Blamco mac & cheese and sipping a glass of Sunset Sarsaparilla out at Dot's Diner.
Shiny new medical robots tended to those who suffered from mundane illnesses and injuries, while on the surface world billions died of radiation sickness, burns, starvation and violence. Housing wasn't as spacious as on the surface, but there was plenty of room for several hundred people, and the vaults that held a full thousand or more could work out fair ways to share their bunks for a while.
Each vault was run by a leader called the Overseer who ran the underground community from a command center deep inside the complex. The Overseers were, usually, selected for their exceptional leadership skills, and the vaults had a security team to "keep the peace" using top of the line pre-war weaponry.
