Not the most original idea for a game, I know! Use the up and down arrow keys to move the "paddles". Pressing the space key resets the game back to its starting state. The scorekeeping doesn't work right - sometimes either the ball goes right through the paddle and hits the wall, or a single hit by the paddle scores more than one point. This probably has to do with the number of steps the ball takes - it sometimes goes past the front edge of the paddle before it realizes it has made contact, and sometimes it counts a second hit after it changes directions. But I've fussed with this long enough and just want to post it as is; I can debug it later.
