Underwater survival hit Subnautica has sold over five million copies, according to data from The aquatic adventure released in January of 2018 following an extended period of early access, and has amassed a respectably-sized and dedicated following. The developer, Unknown Worlds Entertainment, was known for its previous title, Natural Selection 2, which itself was a full-fledged release based on a game modification for Half Life 2, created by Unknown Worlds’ founder Charlie Cleveland. 

In Subnautica, players control a silent protagonist in first person perspective. Said protagonist is the sole survivor of the Aurora, a spaceship that crashed on the ocean world 4546B in uncharted space. The game is non-linear; you step out of your escape pod and explore the surrounding environment in order to find resources that will help you survive. An optional storyline can be progressed through seeking out distress signals and other clues.

Subnautica was released to rave reviews, with reviewers enraptured by the unique world and gameplay. Some, however, were more mixed in their assessments due to the fairly large array of technical issues and a lack of certain features such as co-op. Nevertheless, the game was a popular purchase on Steam following its launch, and has maintained positive reviews since leaving early access.

Unknown Worlds released a new Subnautica game into early access on January 30, 2019, titled Subnautica: Below Zero. This title is not an expansion or spin-off – rather, Unknown World’s maintains that it is a full-fledged sequel to the first game. Set in the arctic regions of planet 4546B and starring a new, voiced protagonist, anticipation for the new title rivals that of the original game. Subnautica: Below Zero releases sometime in 2020.