The combat confused me. I don’t remember seeing any explanation for the timed attack thing – it just popped out and took me by surprise, and even then I couldn’t really tell when I was actually supposed to push the button (this was worse for guarding than attacking).
Another thing that I realized just as I was giving up is that there was a random note in the beginning about certain things taking more oxygen, and I think one of those things was “dash”? I had enabled auto dash out of habit, and didn’t really make the connection initially. If dash is going to have such a negative side-effect, I’d personally recommend removing the auto-dash option entirely (and probably make mouse movement not auto-dash too).
Anyway, I didn’t get very far, but what I saw seemed pretty decent. It just needs a bit more polish to be really good.