The Subnautica games are a series of open-world underwater survival games developed and published by Unknown Worlds Entertainment. Set on the fictional Planet 4546B, the original Subnautica follows the story of Ryley Robinson, the only survivor of the crash of the Aurora, as he tries to survive on the alien planet, investigate the crash, and return home. This planet is mostly water, and has big predatory fishes. There is also remnant Alien ruins of the Architechs to contain the Kharaa Bacterium.