A house in which the current occupant can see branch/parallel universes forming each time a choice is made or an action is taken.
So the occupant decides to walk into the kitchen, and suddenly there are three or four copies of them, walking towards different rooms. The occupant opens the fridge, and a copy opens the freezer, while another copy moves towards the pantry. Meanwhile, the copies in different rooms are exhibiting their own behaviors.
The copies do not disperse until the person leaves the house, and so the longer one spends in the house, the more inundated with branched copies they become, each and every one of them continuing from the initial branch point. Not sure if the copies should make their own copies.
Right off the bat I imagine there's the problem of a hook, but my first concern is if this idea is workable.