The oxygen is a cool mechanic, but it seems too dividing. I've seen that some people think the game is very hard, but after getting infinite oxygen, for me, it was very easy, since the difficulty doesn't seem to increase. Sure, there are more enemies, but they are still slow and still die in one shot with 1 attack buff. It's simple, it's short, and the visuals are pretty cute, I just think the gameplay could see some improvements. Good game!