@Moski Thank you so much for the feedback! Believe it or not, Crypt of the Necrodancer was one of the inspirations I had for making this.
As for the boss, I feel that his mechanic was unclear to players. In order to damage him once you need to hit 3 shots consecutively. Since he changes color every time you shoot him, you have have really good reactions to shoot the right color on the next beat. If you shoot the wrong color, or you miss the beat, your combo is broken and you will not deal damage to him. Looking back on this, I felt like there wasn't enough feedback to let the player know whether they are fighting him correctly. I have actually modified him in my current version to fix this. Now, hitting him will deal one damage as normal, but if you miss a consecutive shot, his health will immediately reset back to full health. This means that each shot, you can actually see his health going down, and when you miss a shot, you can see it go back up. This also means that you only need one "combo" to kill him, apart from three in the original version. I'm not sure if I should upload these changes, would that be against the rules of LD?
Again, thank you so so much. Btw, that twitter link in your message doesn't work. :( I would love to keep in touch with you guys! <3