This was fun! It was the kind of game where I wanted to keep playing, even when I died and was unsure of the mechanics. Great work there!
My main recommendation would be to make the upgrade stations usable with a hotkey rather than walking on them. In my first play-through I accidentally walked on one of the upgrade pads and couldn't figure out how I did that or how to exit the menu.
I did have some performance issues on a Chrome-based browser, but that might just be my laptop.