Basically, under the board there is an electric motor with an off-centre weight that makes the whole thing vibrate at different speeds. The cars are on thin plastic fins that let them move when the base vibrates. No instructions, so I'm not entirely sure how you might play it...

Working - although the correct battery will be hard to find. I tested it with 2 D type batteries strapped together with a wire across the other end.

Generally very good condition throughout. There is a cardboard cover for the motor which has come apart, two of the corners of the box have come apart and the top is slightly bent in.

But overall, a rare item in very good condition for its age.