How to play Pickaxe Pete on Mac

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 of the screen, a key which floats to the top, or nothing. If Pete has no axe, you can either jump over boulders (gaining him 1 point), or get to the bottom of the mine to retrieve a new axe (gaining a 5-point bonus). If he collects a key then he can enter the doors, which lead him to the next level.