Key things to do:

• Have the ball bounce off both paddles
• Have a scoring system to tell who is winning

Possible advanced features to add:

• Create a computer opponent where the paddle follows the ball as it moves
• Add more obstacles for the ball to bounce off
• Create different controls such as using the computer mouse
• Have the ball speed up as the game goes on
• Have the ball randomly speed up and slow down
• Add extra balls
• Changing backgrounds based on the score
• Play sounds when the ball hits a paddle