Fallout is a post-apocalyptic video game set in an alternate version of the United States after a world-wide nuclear war. Players take on the role of a Vault-dweller, someone who has been living in an underground survival vault for over 80 years since civilization ended. The player must go out into this strange new world to find a replacement water purification controller chip or else their fellow dwellers will suffer from dehydration or be forced to leave the safety of their home. They will face mutants, radiation, gangs and violence as they search for the chip that could save them all.