I realized I had to download the game, because the web version didn't really look like the screenshots. I think there's some kind of issue with rendering the water in the web version, because the surface of the water is invisible, which makes the game much harder to understand visually.
That helped the readability of the visuals a lot, but I think one of the remaining challenges was that there wasn't a separate animation for diving - it just looks like you're falling, which is pretty confusing at first. That combined with the fact that there's only one button for flapping/diving/gliding, it's pretty ambiguous what's happening in the beginning when you're still getting used to the controls.
The controls themselves are also a bit awkward. The dive/glide/flap all on one button works well, really, but the mouse controls feel quite awkward. Making the camera's rotation speed relative to the mouse's horizontal position is a pretty unusual choice, and it feels slidey in a way that I think will be challenging for folks that have trouble with feeling motion sick while gaming.
This is made a lot worse for folks with multiple monitors! You aren't capturing the mouse, which means moving the mouse outside of the game window and putting it on the opposite end of a second monitor causes the camera to rotate blisteringly fast, especially when the hawk is at a standstill. I'd highly recommend using `Cursor.lockState = CursorLockMode.Confined` to prevent this and confine the user's mouse to the window at the very least.
Overall, though, the concept is really interesting! Flying mechanics are really challenging to get right, and this is a unique and engaging take on it that I think could just use a few tweaks here and there. It's good that you can't grab fish while just sitting on the bottom of the lake, but the height of the fish vs where the bottom of the lake is feels like a pretty small range, so it often feels punishing when you smack against the ground, and it can be maybe a bit too tough to maintain the correct height, especially when it can be hard to tell how high you are and how high you need to be to catch fish. Some kind of height meter or indicator could help with that, but I think deeper water could also help the feel of things!