Very nice little game! It looks amazing and I like the mechanic of having to choose between an upgrade and how it might make the enemies stronger. The only thing I would critique is that it would be nice if there was something to spice up the gameplay and add something other than running away from enemies and shooting behind you. I made it all the way to level 40 without getting hit once, so many the difficulty curve needs a bit of tweaking. That being said! This is a game jam of course so difficulty curve is really hard to get right. Very nice submission and good job.