At the game page, click Start Game and use your mouse's left button to get the green ball going, then your mouse moves the hand/paddle to cover the ball which starts coming back at you faster and on angles depending on where it hits the other walls.
I got up to level 4 and 9200 points. But I've just begun. Oh yes, mark my words.
UPDATE: Level 5 and 10,345 points. I have to stop now or I will never get to my annual Friday fish & chips and Guinness and Daily News break. Thank you.
Click to Play!