У вашего броузера проблема в совместимости с HTML5
Working on a side-view tank plaformer game. Got the tank working with physics. Still need to figure out how to stabilize the tank when it's moving on a flat surface. It just keep rocking back and forth too much. The road wheels seem to be bouncing up and down a bit too much, as well, when there is no reason for them to bounce on a flat surface.