Cassette 4: Tennis

Contains seven more chips than Badminton. As a matter of fact, the differences with Badminton are the player motions (vertical only in Badminton, bi-directional in Tennis), the condition the system uses to produce a beep (when the ball is caught in Badminton, or lost in Tennis), and finally the central line (net) which is indeed thiner than the wall in Sparring. The answer is simple: by design, the system can only produdce two players (of variable size) and a ball, hence the need of additional chips to draw the central line in Tennis. Sparring does not require those chips because the second player has an infinite height to form a wall.