@magnus-lindh I appreciate the feedback! It does appear to be a confusing game that some extra clarification may be needed for. The basic explanation is that every 10 seconds, lightning will strike, briefly light up the outside of the house and show the silhouettes of the enemies outside. Once the lightning has stopped and it's dark again, you must click on any of the windows/door the same number of times that you see enemies near to it. It is randomised which window/door an enemy will spawn near and try to get to. If an enemy is still alive after 3 rounds of lightning, it will get inside the house and the game is over.
Hope that helps to clear things up if you choose to try it again!