Not knowing if re-downloading the zip file would solve your problem, I decided to update the game so that it's now possible to resize the game window after exiting fullscreen mode using the (ALT + Enter) shortcut.
If you have the key, you can enter the house through the front door by the doormat, you click on the dooor to unlock it with the key then you push it by walking. The game is based on a physics engine, and aside from the map borders and some plot steps, I've chosen to give players the freedom to do whatever they want and explore freely. Unless you found a way to fly using the ladder—in which case I should fix that bug—there’s no problem if you just used it in a creative way to get onto the roof. Thank you very much for your feedback.