I love the exploration and the animations!
Though I will say - I don't think the combat timer is as much of a challenge as you think it is. It's optimal to just spam the spacebar, only occasionally switching options (assuming the player even has any alternate options that run). So the timer is more just an annoyance than a challenge.
Something that could make combat more interesting is if the player could choose to move around in an attempt to dodge enemy attacks - but, the more you exert yourself, the more oxygen you use up. Which would help tie the combat sections with the exploration sections a bit more.