Cool! Quite an abrupt ending but the final level did give me a challenge. The boss fights in comparison were a breeze. You could just go to top/bottom lane and preshot couple of times just as the enemy was about to be there and then just rinse and repeat few times. Worked every time no matter how fast or aggressive the bosses got.
The tutorial was also a bit weird as it had a strict shot limit as the base game didn't have anything of the sort. The bottles were also hella fast compared to any actual enemy in the game and since they fell vertically, there was less room for them and thus less time to react. But yeah, still very doable once you realize that you can take your time and need to aim carefully and land all shots instead of rushing for trying to get all bottles or something.
The normal level difficulty increased in a pretty nice curve. They just got kinda long and tedious with no room for errors which wasn't super fun. You only had a small section of the screen you could really use as being even near the edge could instantly end you and even from a fair distance away, recoil and being ambushed by a fish could spell doom quickly. Taking it really carefully and slowly taking (mostly the eels first) seemed like the best strategy but surely not the most fun one.
One way to combat the edges being unusable and dangerous would be to have some kind of danger markers showing where the fish were about to spawn or come from. That could actually give the player a fighting chance to get out of there to a more appropriate spot.
In addition to the edges being kinda unfair, the enemy/player hitboxes also seemed very iffy and difficult to estimate. Quite often I died without the enemy sprite being even really that near to the player sprite. That same hitbox worked just fine for detecting enemies getting shot but doesn't feel great or fair when it's used against the player. I'd go as far as have that collision box be way smaller than the sprites themselves to allow more close calls and places where player feels like they barely got away in time. Kinda what now happened with the eels sometimes as their hitbox was also kinda wonky.
I did like the way the recoil was something you really needed to take into account. But I didn't really like the dual button thing for shooting. It didn't really bring anything extra in my opinion besides some awkwardness. Quite often too for some reason the game didn't register the right click and popped up the default browser context menu which wasn't fun. Few of those times could have been me just clicking around the game area but some for sure were inside it too. Once this happened to me in a boss fight and after quickly closing the context menu, I couldn't move anymore. The boss was at like one hp left so I did get past it and the keys were back to normal on the next level.
A very minor thing but having to press enter (quite far from both wasd and mouse) at times felt annoying. Other times you had a proceed button there which would have been the better way to go all around. And I think sometimes it even needed both, was it the boss introductions that first showed the button and then still required an enter press afterwards.
The sound scape was a bit barren. The sounds that were there were nice and all but some variation and more of them for the actions that didn't have any would have been welcome to make it feel more alive. Some splash effects, spicy death sounds and other enemy sounds just to fill up the void. Of course the music helped the current few sounds from getting too repetitive but more would surely be better.
Anyways, good job! 👍