Set in the dark aftermath of a world-wide nuclear war, Fallout pits you against a new, twisted world in a fight for survival and the safety of your home; possibly the last remnant of "pure" human beings. Fallout opens with a conversation with the Vault Overseer, the man who supervises and cares for everyone inside the Vault, a hi-tech nuclear bunker shielding the inhabitants from the harsh outside world. The Vault Overseer describes to the Vault-Dweller, you, the Vault's new, grave situation. He informs the Vault-Dweller of a pure water shortage, after the water purification chip was fried. He sends you outside the safe confines of Vault 13 to retrieve a new, working water chip, before it's too late!