Man wasn’t entirely unprepared. In North Eastern America, an experiment was hastily started in the beginnings of the war. A selection of two hundred people, half man and half woman, were chosen solely for their genetic potential and diversity. They were to exist in this hermetically sealed vault which, like a biodome, contained its own sealed environment. Renewable power, gardens, and sealed supplies rated to last over a hundred years. Four such vaults were planned, each with a similar profile of denizens, stores of technology, and renewable supplies. Alpha, Beta, Gamma, and Delta. Since they are impossible to open from the outside, nothing is known about Vaults Beta and Delta. The story of Vault Gamma, however, is all too obvious. Vault Alpha, the one destined to become Vault City, was erected near what used to be Chicago.
Those years did pass, and eventually, the sensors placed outside Vault Alpha deemed it safe to exit. Soon after they did, they realized the extent of the damages. Vault Directors and prediction computers alike decided the same thing: To exist, they must maintain genetic and social purity. Thus, Vault City was built, its wall erected, and the Rules decided. Outsiders would be allowed to shop and trade(after receiving Day Passes of course), but living in Vault City would prove to be a near impossibility if you aren’t decended from the original dwellers. Races other than Human, Elf, and Dwarf are flat-out refused. Even racial subtypes of the above have slim chances, and even human changelings or “mutants” are refused without further consideration. Even those who make it to the test must prove that they have no mental or physical conditions, are free of lingering radiation, and have useful skills that would be a boon to the Vault Citizens, something that would can not simply be attained from within. Day Passes, however, are much easier to get. Guests can visit the city from 6am to 6pm. They can be attained simply through a quick application process and a cursory glancing over by a vault doctor to ensure the applicant has nothing contagious.
So, one can guess the Vault Citizen’s reputation among the other survivors of the Wasteland. Despite this, they are willing to trade their surplus with wanderers, and their surplus sometimes contains things one can not find anywhere else. They open their bioware and cyberware labs for humans, elves, and dwarves that have attained Day Passes. They can grow cultured bioware and install alpha cyberware, but, of course, they know how rare labs like their own are.