You wasted points on this question, GOOGLE, But anyways its a game, or horror genre game, and its fun actually recommend it, That is if your not afraid.
Answer:
As per Google's dictionary, a door is a hinged, sliding, or revolving barrier at the entrance to a building, room, or vehicle, or in the framework of a cupboard.
So, if a door does not barricade anything, it is not a door. It becomes a thick sheet of wood.
1) Try writing out the notes in the following major scales: C, G, F, D, B♭, A, E♭. 2) Memorize the formula: whole, whole, half, whole, whole, whole, half. 3) Memorize some key terms: half step, whole step, key, major scale, root.