Very fun!
I got up to level 16 somehow on my first try even though I didn't even know where I was on the screen half the time, lol. My only recommendation for this game would be to change the upgrade menu button to something closer to the WASD and arrow keys. Escape is a bit too far up on the keyboard and 'P' seems a little too far out of the way for either one. Maybe 'V' or 'B' would be better for the WASD setup. Not sure for the arrow keys though.