Interesting game! I enjoyed the story and the feeling of progression throughout the game. I like how you reused the boss as an enemy later in the game as well as had different types of projectiles. I was a little confused by what the graphics meant but I enjoyed it overall.
If you wanted to improve, I suggest optimizing the game for speed running by putting the enemies on a timer of when to shoot and adding some sort of high score based on time for the main menu.
Overall, fun game! Check out my game if you get a chance!