Subnautica 2 Xbox Series X|S / PC Digital Key is an underwater survival game set on a brand new alien planet. This is the next chapter of the acclaimed Subnautica universe, developed by Unknown Worlds, known for Subnautica and Subnautica: Below Zero . As one of the Pioneers, you find yourself stranded on an unknown world after the colonizing ship CICADA runs into trouble and its artificial intelligence insists on continuing the mission anyway.