I think ocean creatures could really help elevate this game above stuff like Minecraft. You could have ambient, small fish, just there for aesthetics (like the underwater equivalent of birds), larger fish, reptiles, amphibians and crustaceans that you could maybe domesticate or hunt (or be hunted by), and hopefully some sort of fishing mechanics. Maybe you could search the seabed for clams or treasure, or spear fish swimming upriver, a la salmon.
Hostile ocean creatures could really help make building submarine structures more challenging, or maybe just to be cool. Like on Kuehok, in the big, murky ocean underneath the floating islands, you could have some sort of sea monsters to gobble up poor players and animals that fall in.
I have concept sketches of sea creatures I drew up earlier, I’ll see if I can find them. They don’t really fit the Oort art style too strictly, but they’re pretty cool either way.
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