Hello. Thanks for the detailed feedback. I do agree the patterns are very simple, maybe due to the nature of the game (x-axis only and relatively short screen), but also because I'm not at that level of programming yet, so I prioritized gimmicks over intricate patterns. In that sense it's probably more like older shooters than Touhou, though I did take a lot from Touhou. I have trouble designing levels; stage 2 in particular I've barely changed since I first made it, so it's shorter and less well thought than the other levels. Thanks for reminding me to redesign it. Adding health bars to the bosses would be relatively simple; I'll see if I can do it.
I changed the palette of the game since the last version, so it may have messed up the contrast between the bullets and the background, especially in stage 2. I'll revise it; I also hate when I can't see the bullets on screen. Those static circles I have instead of enemies have been the exact same since the first version. I tried to change them this time when I was looking over the art, but I couldn't come up with anything better (I can't draw), so I just left them as they were. Maybe at some point they'll stop being boring circles.
I think I got something similar to your bug a long time ago, when I was making the options screen, but I can't replicate it at the moment, so I'll have to look at it later. (If you do finish the game, please do tell me if you have any more suggestions.) Thanks for playing!