He stops running. Not because he wants to, but because the floor disappears. One step forward and there is nothing under his foot, just open air and a drop that goes down forever. Below him is a portal a swirling circle of darkness. The hallway is gone. There are no doors, no flickering lights, no walls. Just him and the drop and the slow spinning dark beneath his feet. He falls. The portal swallows him whole and the world goes completely, perfectly black.