An idea that came to mind while working on House of Lost Memories. It could work, but I think that for this game, it would just be adding too much weirdness in one place. So, if anyone wants to use this, or is inspired by it, feel free.

The idea is a kind of haunted house thing. The house has been 'fractured' into different worlds after someone summoned a demon in the basement; there's a present house, a past house, a mirror house, a ghost house, and a hell world. These houses are in the same place. Variations or mirror images of the same map. But you might notice that the outside of the house has too many windows for the number of rooms, that the dimensions don't quite add up. There are too many doors, maybe. Because the house has doors and windows for all the different versions of the interior. Depending which back door you go in through, you might get into the real house or the mirror one.

Once you realise this, you climb through the windows and use various balconies and ledges to travel between the different houses; and when you do certain things, the other doors might appear on the outside. I can imagine the exterior displaying an image built from clickable window/door/wall tiles, which are clickable to look/open/break/climb through (but upstairs windows would require a ladder of the right length). And maybe some of the houses have a non-obvious connection. Like a metal box that's locked, but you can get it open by dropping it in the past basement where there's a dripping pipe, then picking it up all rusted in the present.

I think this is an awesome idea. It would be very fun to write!

WOW!!! The weirder the better!!!
I'm om a group project, this could be a good candidate for that...
Each person taking a dimension but using a copy of the same map, just flipped or rotated differently.
Then someone to tie all the bits together...
Maybe a prolog that the player plays through that summoned the demon. then the "jump" to the present...