Good game, like that old dreamcast game with the little mice. Every now and then I would need a particular arrow and not have one, and while waiting for one to come along I ran out of balls. Doesn't seem fair, really. I'm also colourblind, so I couldn't do the bonus stage or the levels involving colour. Could you put symbols or shapes on the different kinds of balls as well as colour so I can see them?
Some little things - clicking on the pause button a second time should unpause the game, and when there are those switch pieces, balls can seem to float over nothingness before they get across the square, by which time the switch has been triggered and they're on the ground again. Maybe you should check for falling off the edge after they've travelled halfway towards the next square, i.e. where the edge of the last tile is drawn.
Some little things - clicking on the pause button a second time should unpause the game, and when there are those switch pieces, balls can seem to float over nothingness before they get across the square, by which time the switch has been triggered and they're on the ground again. Maybe you should check for falling off the edge after they've travelled halfway towards the next square, i.e. where the edge of the last tile is drawn.