They have! If you go outside and down through the tree row, there are a few houses with one you can enter. That place has a few things to do. (The size basically breaks everything immediately though.)
It only opens once you find the ending cutscene. If you make your way to the right you'll eventually run into a room that is full of desks and a fire. After that you'll need to travel up and find the ghosts up there. There's a video walkthrough on my youtube channel just in case. It goes through everything except for the second outside area.