This is just a quick game I threw together myself - everyone remember Pong? Where you could play against the CPU or another player?
What would it be like if you had to keep the ball from leaving on both sides of the screen?
In this version, there are two counters - the top one measures how long you've kept the 'ball' in the play area (in seconds), and the bottom one how many times the 'ball' has hit either of the 'paddles'.
There are some pictures, and a download.
Enjoy. One thing that I'm gonna say though, the pictures are slightly smaller than in the real game.