I can't believe this was made in 2 weeks, it's so polished! The unique items were all super cool and I loved seeing all the little references, I think my fav item was the Travel Pouch or Sheet Music.
Struggling through and finally beating Immerred was so satisfying, it was a tough fight! I just made it with 3 phoenix feathers and less than 10 secs on the clock... I finished on Stage 5, Difficulty 21 and 48 items.
Some small improvements could be made but most of the comments have mentioned them already.
Maybe you could add an Item index in the menu that shows items as you collect them? Idk how programming works so if that's really hard don't worry, it's not a game issue at all! I just want to read the item descriptions and look at the cool art closer without fighting a hundred Otomos at the same time.
This is such an awesome game, I will definitely be playing it again! Plus I still think there are some items I didn't get (^-^).