Nice, but way too easy
Being able to craft raw materials from other raw materials (esp. iron, gold and diamonds) pretty much ruins the challenge. I had maxed out my gear before I even explored the depths of the map, much less built any buidings; there just wasn't a need.
Mushrooms turned out to be the rarest commodity, b/c they were in limited supply and required 5 plants to craft 1 mushroom. Mushrooms were needed (along with stone + glow bulb) to craft energy in large supplies, otherwise you were stuck scrounging for it from the ground or animals.
Sediment wasn't very useful. It made rocks, but you could make rocks en masse using all the dirt accumulated.
Trees were pretty much only useful for making glow bulb, since there was plenty of coal to be found.
Basically, I just scoured the surface area and shallows for every plant, rock, mineral, etc I could find, then crafted my way down to iron, gold, diamonds and leet gear. I did one or two deep dives with good gear to pick up a few golds and diamonds at-depth, but otherwise didn't bother heading down much. I do like the idea of having buildings down below to restore oxygen, light & crafting, but I just never found the need since I could craft everything with diligence using basic materials up above.
Side note, as a scuba diver myself, I appreciate your attention to detail, eg: using more air the deeper you go, due to boyle's law and partial pressures compressing the amount of air in a space, thus letting the diver suck in more with each equivilent breath the deeper he goes.
I really loved the crafting you had in the game, and really wished minecraft was more creative in its crafting formulas the way you were.
I loved this game. I liked that it was a leisure explorer game w/o a ton of crap trying to kill me; just me and the elements. It's an interesting spin on the miner games.
Great job!