Fun little game you have here! I really enjoyed the underwater effects, and the movement felt good. I have to agree with some comments below that the oxygen timer was a little too short and there was no margin for error. Maybe if you had some hearts that could deplete every second when you run out of air it would help? Overall though really great work! I did unfortunately get stuck and just didn't have the skills to complete it, but I'm not very good at these types of games so that's not really a criticism or anything 😅
You can check out my gameplay video playthrough here for some more feedback (and cringe at my awful lack of skill!)