A CRPG set in a post-apocalyptic Southern California, 83 years after a nuclear war transformed the United States. The PC known as "Vault Dweller" is asked to leave their vault, a fallout shelter constructed to last generations, when the water-purifying chip shows signs of malfunction. Fallout is a relatively short (~20 hours) nonlinear CRPG featuring turn-based combat and a strong emphasis on player-driven narrative and reactivity.