A lot of fun! I should not have just skimread the description because I first missed the controls for the gun so I was confused what the purpose of harpooning the enemies was. I made it to level 4 simply by dodging out of the way and staying near the top where there is a delay before they fire at you. Eventually was taken out by colliding with one as there were so many. Then I found the ability to shoot back and now I understand the use of the theme a lot more. I found it easier to get further just avoiding the enemies though instead of trying to shoot them out the way. I love the way they get launched off screen.
The graphics and audio are a bit simplistic but I really like the harpoon animation, physics and UI.

I have no idea what happens after stage 4 as I was unable to reach past half way through stage 4 after a handful of attempts.

This was really fun to play. I personally think it would be a bit more fun with health points rather than just instantly dying, maybe even having a way to get back health. But overall, great game :)