More info:
Subnautica Dives Down and Discovers the Latest Update – December 16, 2016  
Subnautica – Welcome Video, Concept Art and Info – January 1, 2014 

Find yourself in an emergency life pod that crash lands in an uncharted undersea world. As your adventure begins, you must find food, water and resources in order to survive. Then explore a fascinating, sometimes dangerous subaquatic alien world in search of answers.

Charlie Cleveland, Co-Founder and Game Director, Unknown Worlds Entertainment: Since the game’s beta release in 2014, Subnautica has received waves of positive and constructive feedback from our dedicated players. The team is grateful to the community for the overwhelming support. We are proud to deliver an experience that gamers of all ages will dive into and immediately feel the thrill of exploration and survival in an expansive undersea world.

Subnautica offers several gameplay modes. In Survival mode, you must manage health, hunger and hydration. In Hardcore mode, you have only one life and receive no O₂ alerts. Creative mode allows you the freedom to explore without health upkeep or resource costs.

After five years in development, Subnautica has launched on Windows and Mac (Steam, Arc). An Xbox version is to be released at a later date.