Somewhat similiar to Carax '92, I don't think this is an actual hack, in part because of the multitude of changes. Besides the general cutesy appearance of the graphics, octopi and squid that the enemies drop can be picked up and used as power-ups. Also, large bosses are present. This game is for the PC-9821, so you'll need to use T98-Next rather than Anex86.
Bio 100%'s website has a review of this game with more screenshots.