The Buzzball is your own personal rollercoaster. By powering the two internal motors using left and right control triggers, you can move either of the driving wheels and set the Buzzball in motion.

Once the Buzzball is in motion the pod maintains an upright position until the pilot turns, causing the pod to rotate inside the ball against the direction of travel, which applies a braking force and the pod to lock with the ball. This causes the pod to rotate with the ball until the weight of the pilot and pod overcomes the inertia forces and causes the Buzzball to change direction.

Then apparently, that’s where the fun starts, as the speed and direction of travel will affect the degree of rotation of the pilot and pod from a partial barrel roll to complete and multiple rotations. (Link