I sadly can't rate this jam since I didn't participate but at least I can give some honest feedback :)
First try was a bit weird and I encountered some of the glitches you mentioned in the description (items not resetting properly). So after knowing about the mechanics a bit better, I restarted and got a more generous level seed and was able to finish the game with the second char in this run.
The quality of the art, though generally nice, does not mix well. It's apparent that two different artists worked on this without any time left to normalize the art style. But that's not really a huge complaint in a jam context to be honest. It still takes you out of the experience a bit though. The animations, especially the ufo intro sequence, looks really cool :D I also liked the 3d water effect when the aliens are jumping in. Nice touch!
I was hoping that the soundtrack was also produced within the jam, but at least, the picks are very fitting :) The ufo dance track especially.
Controls worked as expected from a diving game like this and the physics also behaved without any unforeseen issues. Good job on getting that done in such a short amount of time! WASD controls would've been nice to have at one's disposal.
Game play wise, there wasn't really that much to do. It boiled down to "swim down and collect items on the way without letting your o2 run out", at least as far as my experience went. Without the oxygen tank, things were very difficult and it got significantly easier as the game progressed (once you get the oxygen tank). Not sure if that was the best balancing choice. Especially in the early game, you die really quickly if you don't find the fins and the compass quickly enough. A good measure to tackle this may could've been to tie the amount of lost oxygen to the diving depth to make diving in the beginning a bit less penalizing. Kudos on implementing a procedural level generator as well as adding so much variety in animated assets that swim around and wobble in the water (animals and plants alike). Not sure if there are more entities to interact with, but I only found the green spiky thing to be worth of attention since it gives you some o2 back and catapults you down if used correctly.
All in all, good job an a solid, short experience :) Could've used some more variety game play wise, but since it's rather short, it doesn't really overstay it's welcome in the form it's in right now.