Really cool game! I liked the idea and think that it's a really strong base to work off of. The game has a very cosy feel especially the music, which keeps me calm as I frantically move my mouse across my desk trying not to get hit!
As you have mentioned on the page the game could do with some more polish, I ran into some bugs (upgrades showing mid round, game stopping working when I moved my mouse to my second monitor). Was able to just go over an enemy with burst to almost immediately pop them, and the balancing could do with some more work, but for challenging yourself with a bigger scope, you have by no means done badly. (that's to say, really good submission!)