Sometimes I thought that making a game like this would make studying much easier, and you certainly proved this. You should make more games like this one, people may actually learn something while having fun ^^
I'd like to see this game with more dificulty. This game is not bad, but it gets so easy it gets boring. If the maker reads this, take it just as an opinion to improve your future games. By what I've seen in this game you have potencial. Keep up with the good work ;)