Art style feels a bit rough, but it fulfills its purpose. The music, sound effects and general mood where on point for an underwater experience.
I had a really hard time figuring out how to kill the squids. Then I noticed that the small ones where shooting bullets. I only noticed this when a bulled went in front of something else, but this is not a fault on your part. I am color blind and that bullet just blends in with basically every color for me :p
Keep it up.