Very good game, I liked the art style and it was very readable too. I liked the slow introduction of the different enemy, even if when you die at the end, it's pretty long too come back to where you are, but it allows you to get used too the different enemy type which is good. I found the random trajectory of some enemy where a little hard to predict, especially with the slow speed of the bullet (especially the sea shell). But there was a great difficulty curve I think.
Good job.