What is the main story about?
The game begins with the player being literally born and (rapidly and in steps) grows up in the Vault. At age 19 the players father suddenly vanishes from Vault 101 – an unheard of phenomenon, since the Vault itself was locked down since the day the bombs dropped (200 years). The Vault Overseer suspect the player is involved or has further information on this – so the player decides he has better chances out into the wasteland – and may even figure out why his father suddenly disappeared without any word. In short: the player seeks his lost father – for reasons unknown yet.