Thanks a lot ! (I'm lead developer on this project) We planned to make more variety on each section of the world (swamps,trees and plant-related traps and enemies in the forest area, skeletons and ghosts in the graveyard, etc...) but it takes us a while to make assets so we just cut it out (sadly).
You are true, moving room from room is pretty slow because of the wall's sizes (We just never found another way to do that, maybe merge a bit neighbour rooms).
Thanks again!