Fun starting concept. I played it on Chrome and the quit button worked for me.
I would say that one issue might be the fact that the balloons can hit your yoyo in its starting position, so there's no way to avoid hitting some of the red ones.
Perhaps you can have some sort of combos for multiple balloons hit at one time. Make it similar to a casino game where certain sequences (3 of one color, one of three colors) give bonus points. Since the king's pleasure is important, maybe a graphic of the king that progressively smiles as non-red balloons are hit and progressively frowns as red balloons are hit.
Cool concept and I can't wait to see where you go with it!