ith a slow creeking sound the white door opens before your astonished eyes. Unwittingly you take one step backwards. "Yes, it is an open door.", the old man lectures you from above. "It can be used by walking through it. No, simply staring at it will not get you inside the building. By taking the door you have a clear advantage over those who try to climb the wall or dig themselves under the cellar, my curious friend! Ah yes, the door...a very powerful invention indeed!"