The 10-foot sphere is made of the same plastic as Legos, and its curvature helps to cushion players if they fall. The ball spins on a platform fitted with 45 caster-mounted wheels. Beneath, an optical sensor tracks motion the same way a computer mouse does, watching for relative movement across x and y axes. To make the experience truly immersive, the player is fitted with a head-mounted display with two internal LCD screens. A laptop wirelessly collects the data from the sensor and the gyroscopes, magnetometers and accelerometers on the headset to create the image the player sees.