I don't envisage that there will be anything fantastic or science fiction about the game.
The idea came to me whilst sitting in Room 610. In the antechamber to this room (also known as the washroom), there is a mirror which is actually a door. Very occasionally this is left open and if you take a peek you can see rough walls, pipes and metal ladders descending into the bowels of the building. It is a wonderland de nos jours.