Fallout 3

In the far future where Earth has become a devastated wasteland, you're the child of the noted scientist James in the underground Vault 101 that's in the Washington DC area. Upon reaching adulthood, your father has mysteriously disappeared into the outside for some unknown purpose. Soon, you're forced to flee outside yourself from the murderous tyranny of the Vault Overseer who'll not tolerate such dissent. Now, you'll begin the search for your father as your adventures begin that'll either bring hope to that dismal world or destroy it.