Enter a Vault

While roaming around the wasteland of a post-apocalyptic America certainly has its appeal, you've always been fascinated by the Vaults. Developed by the Vault-Tec Corporation with assistance from the US Government (and the shadowy Enclave, depending on who you ask), the Vaults were advertised as the best method to safeguard the American people from a coming nuclear apocalypse. Space was limited, and there was a rigorous application process to be accepted, but those lucky few who got chosen were guaranteed to survive Armageddon in style and comfort, and be ready to repopulate the world once the Vault doors reopened. They're an iconic part of the series, and the majority of player characters hail from one, since they offer a convenient excuse for them to be a 'fish-out-of-water' in the wider Fallout setting.

Of course, the Vaults were never meant to save anyone. The dark truth, which few people outside of Vault-Tec's upper management knew, is that the Vaults were actually designed to be a vast network of long-term experiments to study human behavior and physiology under a multitude of situations. Outside of the few lucky 'control vaults', each Vault had its own hidden objectives and parameters that were carried out on the unknowing population, the results of which were meant to be recorded and sent to a main hub of some sort. The stated purpose of this was to test how humans would react to different scenarios that might arise from prolonged space travel and whether a successful society could be established within the experiment's parameters, but the Vault experiments tended to cross the line into outright mad science half the time, and very few of the 'experimental' vaults managed to survive long enough for its inhabitants to see the light of day, often failing either due to in-fighting caused (in some cases deliberately) by the stressful situations or by the experiment itself having too high of a mortality rate for the population to be sustained.

But with your godlike powers, your Vault can be as successful as you wish it to be regardless of the circumstances. The real problem comes with choosing which Vault will be lucky enough to have you for a resident. There are around 120 Vaults confirmed to exist in the Fallout universe at the time of the bombs dropping, and you could choose any of them to be your new home. You could easily pick from the huge list of canon Vaults (link here) to insert yourself into, choosing either a control vault or one with an experiment that you find interesting. You could also pick a number that isn't already taken and design an experiment of your own for the Vault to carry out, one that you can either let play out naturally or 'guide' towards an ideal outcome using your powers. Either way, you could end up creating an oasis of pleasure in a desolated wasteland... or a living hell even worse than what's outside of it, if that's more your speed.

Finally, you'll need to decide your role in the Vault. The most natural position would of course be that of the Overseer, the person in charge of the Vault as a whole. But you could easily choose to instead be the Vault's doctor, chief of security, head engineer, or even just an 'average' Vault Dweller if you prefer. Ultimately, regardless of what you choose the survival of America, and the human race as a whole, will be on the shoulders of you and your fellow Vault Dwellers. Do with that information what you will.