Since you just released the new demo/build I want to give some feedback. First I want to start by telling you that I was impressed with the visuals, it felt like Metroid but different and it was nice pixel art and sound to enhance the feeling. It did run great on my old potato laptop so that is great work! Kept stable frame rate, good visuals and smooth inputs. I had two small glitches, when a energy pickup was left and I moved away from view distance the purple glow was still there when I came back and the pickup was unloaded. The boss was damaged in its "Serris" attack and it kept doing the sound of damage until it repeated the attack.
I did like what you have done and my main point of frustration was that the breakable blocks where sometimes hard to hit and find. Gave up twice and took a break and then I tried to shoot everything and realised the crack in the wall was breakable but I needed to aim to break it while it looked as my show did connect. So maybe increase the hitboxes.
Other than that I just want to say I am really interested and wants to see where this project ends since I liked what I tested. :)