This game has been pretty well advertised, insofar as I've seen it multiple places online. But, I'll add to that here.
Basically, you need to move the red ball onto the star. You only have a crayon, with which you can draw other objects. You can draw a bigger ball to fall and knock the small one about; you can draw levers; you can draw ropes. It's pretty easy until the later levels, at which point you can abuse the open-endedness of the physics to do whatever the hell you want. You can do that even in the lower levels. I'm pretty sure I didn't solve at least 75% of the levels as intended.
For example, there's ejection when you draw an object partway onto the ball (and the object is stable because it is connected to two "pins" or fulcrums):
But watch out for deficiencies in the engine ;) :
These can be avoided by carefully erasing your previous objects:
I would rate it maybe 6 point out of 10, maybe not worth 20 bucks, but definitely amusing.