This is a really cool game! Congratulation!

Nice idea. I think you should add some laser cannons, aliens or something similar to improve the fun part. Also the numbers are little hard to read and the mouse is reacting a bit slow.

Nice Game. But sometimes a balloon is placed so the equation is not fully visible (-1) and sometimes it is impossible to hit the correct balloon because another balloon is in the way (-1). So 3 stars from here. :-)