Thank you very much for your detailed feedback! I would like to revisit this game at some point and your specific suggestions will be helpful.
I find your tutorial suggestion interesting! I tend to not like tutorials so I often omit them from my own games for the most part. However, I find that many people ask for them when giving feedback, so I've been trying to find a better balance of tutorializing and teaching through play. I like the suggestion to add more juice to the boss and the UI elements so the player learns naturally rather than through reading tutorials, which is how I'd personally prefer to play a game.
I'm glad you enjoyed the game. I definitely need to add some harder enemies and levels. I appreciate you playing it!