Fun: I found the combat to be simple but engaging. Attacking an enemy from a distance and then having to weave between their bullets to get your shell back was cool! The boss designs (of the two bosses I was able to fight) were cool! Boy is this one difficult though. I wish you could regain health in some way at least. There was a handful of game-breaking bugs that lessened the experience for me.
Innovation: I thought the concept of your shell giving you more HP when held was interesting, even if the actual implementation of it made it pretty meaningless. I also thought the concept of a single projectile was done well here.
Art: The art here is superb. The title screen is so cute and the boss and enemy designs are awesome! The actual in-game implementation of some of the assets is questionable though. The way some enemies sit half off-screen felt jarring at times.
Sound: I found the music pleasant and the sound effects sufficient, though there could have been more of them.
Theme: I found the tackling of the theme, an octopus using a coconut shell, to be charming!