Bethesda lead designer and producer interview

Gavin Carter: There's a lot more handling! We spend a lot of time talking about, "What if the player doesn't go where we want them? What if they stumble on this spot that we wanted for the end-game?"

We have to handle that. We don't want to just lock them out and say, "You have to go down this path, that's the only way." We have to handle everything the player's going to do.

Interview - Fallout 3