thank you so much for these insightful feedbacks.
1. yes there were supposed to be additional upgrades that you saw but for some reason when I uploaded the game to itch.io, I think it has something to do with the html, the upgrade ui does not show up
2. yes thequincally you could just go straight down. I tried to incerase the difficulty of enemies as you went down. but I didn't have a lot of time to tweak the enemy difficulty that much so its possible its too easy right now. but I will for sure have to keep working on that in the future.
3. yes other people told me they had trouble with the shop. I think its because I didn't allow for a fullscreen mode. this is only my 2nd jam and so I was aware of this option but I will definetly look into how to do this in future jams.