Great feedback, and I agree. After the first day I thought, this is a really simple concept, I'm just going to focus on polish ... but I kept adding more and more upgrades making things more complicated, not leaving much time for polish.
My biggest lesson is that building a shop system or item select screen is way more complicated than I thought it would be. I need to spend some time on arrays because the initial idea was to only display like six options after a round and you could pay to shuffle the selection ... but I couldn't get it to work and just went brute force to meet the deadline. Even then, looking at it now, I could have at least made that wall of options less intimidating by giving them clear tiers and including the price on the item, or having items you can't afford greyed out.
Thanks for playing and for the feedback!