That is very easy. All you have to do is to place the cursor over the ball. There are many things you can do to make it more difficult. Here are some:
. Hide the cursor;
. Make an acceleration systema for for the bars - "delay" and "friction";
. Use special items to modify the experience. For example: an item inverts one or both of the pairs of bars; an other makes walls relax and contract in a senoid interpolation; an other makes the bars smaller; an other places more balls on the table et cetera;
. Use spherical batters. They make the ball's movement less predictable. An alternative is to use friction between the bars and the ball.
At work I made a "breakout" game that uses two rounded batters. People found it difficult for our public, and I had to make it much easier in other aspects. ^^ I can send it for you to try if you want.
Edit:
Attached a screen shot. It shows the rounded batters and walls moving. ^^
Edit 2:
And what do you say about "rounded pong" instead of "squared pong"? That would be an interesting design. A rounded table with two rounded paddles. That is just a suggestion. I do not want to ruin your focus, because you are doing a good job.
Cheers.
