Very impressive! The level of polish of the overall experience is insane!
An added step to the complexity could be to have 2 sets of upgrades and having the player choose one.
Really enjoyable game!
Glad you found the game to be polished, I tried my best at it :)
Your added step was something I actually considered in the beginning (but eventually scrapped bc it would have taken longer), with a shop sort of thing where the player would buy 1 of 2 upgrades every so often. I like your idea though!