Hey I gave the game a play. Overall it's pretty fun. Here's some random feedback/notes I have
--Art style is nice for this type of game.
--At first I was thinking the enemies are a little too easy and dumb (first open level), but as you layer more on, it gets more interesting. I especially love the creepy horses. I stopped at the level where it's a bunch of rooms and enemies, and eventually it just devolves into back pedal strafe, but for the most part the encounters and level layouts are interesting.
-I like the floaty movement, and it didn't take me long to figure out the slide jump combo to get going really fast. This was in the first open level. I would definitely recommend more levels like that.
--Weapon sound effects are not good. Feels like you're firing a air gun. Here's a good library with gun sounds that I've used that may help: The Free Firearm Sound Library | OpenGameArt.org
--Also along the same lines as the sound, the weapon feedback in general is poor. I don't know if you're opposed to adding screen shake, but there's other things you can do, like more weapon kick and stuff, to make it feel better.
--Some other sounds are weird, like the jump. But enemy sound effects are great.
--Making it more clear where buttons are and what can be interacted with would be good. Like that first boat button is in a ridiculous spot. And then the level to open the temple doesn't look like a level at all and just blends in. You need to come up with a visual language that to tell the players when something is a button/interactable. Then show them at a time when it's really obvious, and as long as you stay consistent (and it doesn't blend in with something else), the player will always be able to tell.
--Using the mouse wheel to scroll through weapons, it's frustrating that it goes to slots that are empty. You should just skip the empty slots.
--I'm not a fan of the dark areas where you need to use the flare gun. Might just be my taste though.
I realize a lot of this sounds negative, but I'm only giving all these specific notes because I really did enjoy the game, so I want to offer some suggestions that could make it better.