I really liked this one! One of my favorites of the jam! So know that the rest of this criticism is really minor compared to how fun I found this.
The risk vs reward balance here is off. The start is too slow (as is, frankly, a lot of the progression). The game has a really strong and successful element of pushing your luck. But it would feel a lot better if your skills were more rewarded. After I pick up my first gold, I can either play it safe and take it back to the ship, or push my luck and try and get one more (which is all you really have the O2 for at the beginning). But because of the procedural cave, it's random whether the next part of the cave has any gold close enough to me. The risk is that my run is lost, but the reward is only maybe there's a gold around the corner.
The first and simplest fix for this would simply be making the gold a little higher value. It's often just not worth going for one more gold when if I take damage, I've basically negated it. The second fix, would be to actually not always regenerate the cave. Have it so that when the player returns to the ship they can either stay or move to the next cave. That way another skill is being rewarded: exploration and memorization. As it stands, the only skill that is rewarded is speed through the cave, but that is in friction with the ever changing layout.
I really liked this game!