This is a surprisingly simple and entertaining game. I want to say I posted it already, but I don’t think so. Anyway, you can make cool music by drawing lines and watching the balls bounce off of them. The length of the line changes the tone of the sound that comes out. You can change the strength of gravity, and the speed at which the balls drop. If you make a box, the balls will bounce around in it forever, giving you a headache, but then you can move the line at the bottom, and watch them all fall out.
Try it out for yourself