Nice way of flipping the limitation.
Visuals we're very nice, audio as well. The gameplay was enjoyable, stayed for the entire 10 minutes :)
Small suggestion by me: maybe communicate what the upgrades do, for example: I had no idea how the gun upgrades work, I just skipped them entirely on my final playthrough, because at least as I understood, they would just replace my current gun, with no apparent benefit. To be fair, having some obscurity on the upgrades, made me try them all, so there should be some balance in that regard.
I think you have ideas for the future already, if you plan on developing further: more enemies and upgrades are the obvious suggestions :D maybe some dynamic level/map events, could be a fun additions as well.
Overall great game <3