I remember a fellow around BBW-chan a while back had plans to make a fallout themed game. His name was Das-Amigos, he seems like the type to join up if he ever comes back. Anyways, his fallout weight gain game was based inside a single sealed vault and you would have played as an omniscient overseer of sorts and could fatter the residences and all that good stuff.
I don’t know if anything ever became of the project as he sort of disappeared before the game left the conceptual stages.
It’s a good game concept though as it keeps the scale small and controllable.