I love the atmosphere of this! Although I did spend a lot of time looking at the map when I was down to the last few BEP15 cannisters. But overall it felt as authentically Cambrian as I'll ever likely experience.
I didn't encounter any game-breakers, but there are some typos:
Hallucigenia's riddle: "In the morning I walk on three legs", when the answer says that in the morning it walks on four legs.
The other typos aren't part of the gameplay itself, just the end credits:
"Expect that one boop noise" - *Except
"Paleonotology Coproliteposting" - *Paleontology
I'd have expected to see the controls displayed from somewhere in the Esc-menu (to check them in-game since I didn't remember them all from earlier) but the controls are pretty standard, so not hard to guess them if you're familiar with FPSs.
I can't think of anything more to add. So many cool critters and sponges! And the hidden game was a nice touch. I wonder if there's more stuff I should look for...