From the brilliant game designers at Gamedesign, here's Tennis. This game couldn't be simpler, essentially aping the controls on my old copy of Mario Tennis for the Game Boy Color. Use the arrow keys to move, the space bar to swing. As with the best games, the controls are simple, it's easy to get started, and then the pain begins. This is not an easy game to win, but a lot of fun to play. Great for a match or two in exhibition mode, or do more in tournament. By the way, Gamedesign has a ton of stuff like this.