In Fallout Shelter, players build and manage their own Vault as an Overseer – the leader and coordinator of their Vault. Players guide and direct the citizens of the Vault, and need to keep them happy through meeting their needs such as power, food, and water. They rescue dwellers from the wasteland and assign them to different resource-generating buildings in the Vault, using the SPECIAL statistics system from the other Fallout games. Each character's SPECIAL profile affects their ability to generate different resources, and their statistics can be increased by training them in rooms devoted to each stat. The dwellers can level up over time, increasing their health, and can be given new items and weapons to help with various tasks. The number of dwellers can be increased by waiting for new dwellers from the wasteland to arrive or by pairing a male and a female dweller in living quarters to produce babies.