I'll start off with some (hopefully helpful) criticism.
The graphics text at the beginning was a little difficult to see in some areas, maybe an outline or different color to the text would make it more clear. Subtitles may have been nice as well since the robotic vocal effect, music, and other sounds made it a bit hard to hear the voice-over. It kinda hurt to spam my mouse, so maybe it would be better if you could hold it to fire (maybe just more of a personal preference). The enemy spawning particles were the same color as some of the enemies which made it a bit hard to see them, contrasting colors could be nice.
Now for the good.
It felt satisfying to shoot and the ability to right-click to aim was a nice touch. The upgrades gave a good sense of progression and made things more fun. The visuals were bright and stylish. The maps were large, roomy, and were nicely detailed. It felt like a lot of effort and love went into this project. Nicely done.