You start walking down the corridor. After a few seconds, the hallway starts to get wider. Feeling a little more comfortable, you keep moving. At the end of the corridor is a brick wall. You look around, but there's nowhere else to go. Without warning, the floor disappears from under your feet. You drop down to the hard floor below. A small stabbing pain goes through your legs, but you manage to stand up and brush yourself off. Looking around, there's only one way out - and that's the corridor across the room.