Use the arrow keys for Player 1 Use W,S for Player 2 And use the mouse for selections. Tip: Hitting the ball on different areas of the paddle will aim it in certain directions Be warned: the CPU cannot handle more than 1 ball. This is because one variable that is used by the CPU is shared between balls. This is the reason that you don't see any multiple ball games for 1 player.
The paddles are shaped weirdly because it enables you to hit the ball on the edge. (It's also filled in to prevent the ball from shooting straight through it.) Feel free to Remix this and create your own modes!