Solid jam entry, nice work! Absolutely love the main robot character<3
Some feedback; I would've liked the upgrade system to popup during gameplay and not be found in the main menu. At first I played without upgrades which felt kind of interesting with having to click each row of enemy and optimize that. As soon as I found the upgrades I quickly became overpowered.
Keeping progress tied with currency for upgrades is in some level interesting, but I would seperate the two as you probably never want upgrading your abilities to feel bad.
I would try increasing the speed of the bullets and the enemies by like 3x, would make it much more intense.
I hope I don't come off as harsh, great job on finishing a game!