The goal of each level is deceptively simple: Make the ball move in a way that it touches the star. How you make it happen is wide open (best just to see the video trailer).
Editorial note: Whoa! You've found a super-old post here on BuzzFeed, from an earlier era of the site. It doesn't really represent where we are anymore, and may in fact be totally broken, but we're leaving it up as a part of our early history.