The handler of the object types 50 and 51, which are creatures that harm the player and wander about the room. A creature stays just above the floor, and walks along one axis at a time, at a speed of four. When it has no speed, because something has stopped it, it picks a new direction at random: along x if it was stopped along y, and along y if it was not. The lowest bit of its type and the flag for the sprite being mirrored are set to show which of the four ways it is going, to give the right picture.