Pick Axe Pete!

You play a miner named Pickaxe Pete, and you start off in the middle of the screen with a pick-axe. There are three doors from which boulders are coming, bouncing down the mine-shafts; every time Pete destroys one of these he gains 3 points, although the axe wears out after a while and disappears. When two boulders collide, they explode, and out comes either a pick-axe which floats to the bottom o...