"The first in-game art assets are being created, soundscapes are being recorded, and animations are starting to slither, turn and swim. We have created a rich library of concept art, and set about designing and iterating on core elements of gameplay," wrote Unknown Worlds' Hugh Jeremy in the game's reveal post. "Subnautica is not in 'alpha,' it is an idea that is just starting to be mold into its first playable incarnations."
With that said, there's no launch window. The game's development will flow along now with community feedback about what they'd like to explore under the sea.