It’s a really great example of an open-ended interactive toy being very engaging indeed. Any competitive elements are really set by yourself, if at all, the ‘rules’ of the system are simple. You draw lines and the little fella rides them like a miniracer car - all gravity-driven.
I challenge you to be bored by it. If you want to see some more complex forms in action you can check out some videos people have made on YouTube.
I wish it wasn’t hosted on the incredibly slow Deviant Art site though.
(Thanks to Monica Monin for the links).