I looove the art style, especially the boss!
The game was easy to understand and the length of the gameplay was just right. I enjoyed seeing the variety of enemies and their attacks.
The music is fitting and the quacks were super cute. Though I think I got a mini heart attack every time I got hit because the impact sound was a bit jarring haha. But not really an issue since you have volume sliders (yay!).
I was able to win with the normal bullets and had a lot of fun in that mode. But when I tried the piercing ones it was a bit more challenging since I couldn't really tell whether I hit the enemies or missed them as there are no visual cues for when you land hits. The enemies randomly have more health so having that cue would really improve the experience. But I understand that with the time constraint you probably had to prioritize other things.
Overall a well-scoped, solid game. Great work!