I am also a fan of changing maps while u walk on them, mean like Silent hill.
If u reach a spesific spot the map changes to a twisted Version of it.
the pic here is not a very good match but imagine walking in KM or Tokyo and swap u are on a different map, twisted Version of old one. somting like that.
Show here is a distopia scene.
but it could easy any theme u can imagine, Hellscape, Flesh Prison stuff like that.
It does not need to be the exact copy of the map, some houses might be able to enter that are not enterable on normal map, you can use complete differen mobs here.
You did this in SA with the day night circle, but I imagine something more like silent hill, walk on normal map, and woop you are on a different one with other maps, more danger maybe…
It would be fun to fight on an distopia NY map (after the nuke strike) or in London (all is a hell Zone demons did conquer London) or Seoul (maybe different time, during Korean Japanese War, Seoul is burning and you fight filth Samurai or stuff like that.)