Pixel art was nice, and music was very good.
Boss fights were very cool, but first two had too little health so were over a bit fast.
Last one maybe had a bit too much health, but I think mainly could be improved by making the damage you take greater, but also giving you heals. That way if you have a bad first phase its more recoverable.
Would also be nice to have an indicator for where the last enemies are since its a bit tricky to find them in the level.
Although the theme is present, it would be nice if it impacted the gameplay more actively as it's mostly in the story.