Want to improve your math? Play my game!

Classic space invaders with element of math inside!
I will make a huge update to this game 1 month later, which will include things like shop and new levels!
Here is the link on Google Play Store:
https://play.google.com/store/apps/details?id=com.JigglyHippopotamus.MathShooter

Everyone is welcomed to give comments on my game!