Will update this with more ideas if they come to mind. Not sure how well this one will fit, but it came to mind as I was freshening up for bed, and I'd forget about it if I just wrote it down in my notes app.
Summary
A claustrophobic dungeon flow that slightly deviates from vanilla themes such as factories and mineshafts. This one could be closer to something like the mansion I suppose, and may even come with a new entity.
Hallway tile
Behold... an old ass, creepy wooden house featuring long, dreadful hallways. Complete with a pale floral wallpaper, popcorn ceiling and a yellowed carpet. Another version of this hallway may feature a light wood instead. Both hallways would be just wide enough to fit two players side by side. This aesthetic kind of reminds me of the ghost girl, now that I think about it.