The general idea is nice, but there are really a few problems. Most of them have been mentioned by other users already, but I'm still going to name some:
- Player movement speed is much too low.
- Controls could be improved.
- Reloading system annoying and useless.
- Difficulty quite high after wave 1.
- Game does not pause in the upgrad screen. (Seriously, wtf? Why on earth would you do that? Especially when the game kinda turns into a bullet hell shooter after some time~)
Also the graphics were rather unspectacular. I'm not a big fan of some geometrical shapes hovering around and shooting each other, although there qre quite a lot of games like this out there. Go back to the roots and give us some space ships or anything more fancy than boxes.