Haunted Chair is an enemy appearing in Big Boo's Haunt.
The haunted chair behavior actually accounts for two different kinds objects: The chair in front of the Mad Piano, and the other haunted chairs. The two cases are distinguished by the distance from the chair to an object using the Mad Piano behavior.
The first case occurs if there exists an object with the mad piano behavior and that object is within 300 units of the chair. Then, the Mad Piano is set as the chair’s parent object. When the lateral distance between the chair and Mad Piano is less than 250 units, the chair will begin to fall. The chair can fall in one of four directions separated by 90-degree angles, with the direction being dependent on the angle from the Mad Piano to the chair. In three cases, the chair will fall being rotated 90-degrees, but if Mad Piano approaches behind the chair, the final angle will be 112.5-degrees. The chair falls by rotated toward its final angle at a rate of 8.24 degrees/frame. Thus, the full rotation will take either 11 or 14 frames. The chair will remain on the floor with no further actions.