The only way that you can play it is if you can see the hologram. Here's a hint. To beat the computer, you must hit a glancing blow off one side of the paddle, so that the ball goes into one of the two top corners at a sharp angle. It requires no mouse clicks to move the paddle - just left and right mouse movements.
Here's the URL for the instructions. The link to the actual game is on that page.
http://www.dtek.chalmers.se/~d3rebas/creative/martinsoft/spong.html
ENJOY!