Someone said it was copy of "some anonymous" other game. If it is copy, or inspired by some other game, please, source?
Anyway, loved it, bugging was little annoying, when balls sometimes get stuck, but that never was too bad. Especially after I found out you can use 0-9. It was so good, that I had to get account in newgrounds just to review this.
Game twisted my brain from the right spot. It was also very enjoyable to watch balls fall after calculating carefully paths. It's hard to find games that have new concepts (to me) and that brute force was not the only way to solve.