This is such a clever idea for a game!
I could see this as a full puzzle game, maybe instead of disappearing you have to get all numbers to zero and so you have to plan the throws out exactly. (or you make them -1, and lose)
The sound seems to just on the left side
I found the way the characters move away from their original spots to catch confusing at first because they didn't line up with the numbers any more. But then I realised it works both ways and not to throw at the character but where I need them to be.