Really liked the game but could not finish it (8/10 gems) because the yellow one which you had to unlock by headbutting a projectile 2 times was too hard for me. Except for the headbutt mechanic, which I find a little frustrating, the rest of the game is amazing and I've had an enjoyable time exploring and reaching the depths with the fluorescent algae.
Fantastic atmosphere and great game. Hope I could've finished it, but congratulations to the team for the submission! :)