I helped run a Zombie game awhile back because it really was a dream setting of mine. The reality was the constant threat of ZOMBIES EAT U combined with a lack of meaningful systems for resource gathering kinda made the whole thing get old rather quickly? Like, either you are fighting zombies, or you’re running from zombies, or you’re talking about how scared you are because you just fought / are going to fight zombies, and it’s just a rinse & repeat.
That’s the issue with a lot of themes, IMO. The setting seems cool, but there’s just nothing to do.
My missed setting? Cowboys.
It’s never going to happen.