Video games are usually built upon the fantastical, but so often they neglect to nurture a believable fiction. They force their stories down our throats, or fatally undermine their integrity by giving the player too much agency, or claim to offer choice and consequence while taunting us with invincible player characters and predetermined decisions.
Fallout, though, creates a world that feels believable, cohesive and uncompromising, employing subtle writing and flexible, consistent game design in the quest for internal coherence. It forces the player to actually roleplay, working with your character's skills and strengths to see situations play out in all manner of ways. Through individual behaviour and choices, Fallout lets us create our own stories in a way that aspirational developers still struggle to achieve.
