Great job! I agree with the other points below, the simplicity of it is great and was fun just destroying all the monsters. I also really like how you included an online leaderboards and mentioned it from the start; made me want to do even better before even starting.
The white flashing was a bit much though and did feel like I was getting hurt at first. It can get a bit overwhelming. Also remember that constant flashing in a game like that should have an epilepsy warning :)