component responsible for the Vault's water recycling and pumping machinery, stops working. With only 150 days before water reserves will run dry, the Vault Overseer tasks the Vault Dweller with finding a replacement. Armed with the PIPBoy 2000 and meager equipment, the Vault Dweller leaves Vault 13 for the nearest source of possible help, Vault 15, but finds it abandoned and in ruins. The Vault Dweller explores the wasteland and locates a replacement chip in Vault 12, underneath Necropolis. The Vault Dweller returns to Vault 13 with the chip and the water system is repaired. The Overseer becomes concerned about the mutants reported by the Vault Dweller. Believing the mutations are too widespread and extreme to be a natural occurrence, the Overseer charges the Vault Dweller with finding and stopping the source of the mutations. Information discovered throughout the wasteland reveals that humans are being captured and turned into Super Mutants by exposure to the Forced Evolutionary Virus (F.E.V.). The Super Mutants are led by the Master, who intends to transform every human into a Super Mutant and establish "unity" on Earth. The Children of the Cathedral are a front created by the Master, who is using them to trick humans into peaceful submission. To stop the mutations, the Vault Dweller must destroy the vats containing the F.E.V. and kill the Master; the order of the tasks is chosen by the player. The Vault Dweller travels to the Mariposa Military Base to destroy it and the vats within, preventing the creation of more Super Mutants. To kill the Master, the Vault Dweller travels to the Children's Cathedral and locates a prototype Vault beneath it, from which the Master commands his army. The Vault Dweller infiltrates the Vault and can choose to convince the Master that his plan will fail because the Super Mutants are infertile, kill him immediately, or set off an explosion that destroys the Cathedral. The Vault Dweller returns to Vault 13 but is denied entry by the Overseer, who fears that they have been changed by their experiences and the tales of their exploits and accomplishments will encourage the inhabitants to abandon the Vault. The Overseer exiles the Vault Dweller into the wasteland. Fallout concludes with the legacy of the Vault Dweller's decisions on the societies and people they had encountered. Development Development on Fallout began in early 1994. Initially, Interplay gave the game little attention, and