Nice and active shooting game! A bit more text about the game play may be helpful for the player. It took me a while to realize that when two octopuses collide they become a big, target-searching one. Probably because it always happened off-screen in the part where I was not shooting the small ones :)
It's not clear when / why a next level is reached; the counter just increments. I did not get to the end unfortunately. Maybe if the health was reset at each level?