It also appears to have a random? element with regards to ball behaviour. Each run of this https://developers.google.com/events/io/input-output/ahNzfmd... ends up different. Sometimes it hits the wall, sometimes goes over it and sometimes it makes in into the output. (should be two items on your screen - resize until you see a Track and a Wall)

Seems difficult to design and share if ball behaviour changes run to run. Unless that is part of the point - simulating real world user input ;)