Unknown Worlds has sold more than 5 million copies of Subnautica. This does not include free downloads from the Epic Games Store.
The exact total over two years is 5.23 million copies sold across all platforms (Steam, Epic Games Store, PS4 and Xbox One), according to gamesindustry.biz. This news came from the founder of the studio Charlie Cleveland.
In March last year, the Epic Games Store gave Subnautica away for free for two weeks. During this time, 4.5 million people downloaded the game. Thus, the total number of those owning a copy of the title, either free or paid, has almost reached 10 million.
Subnautica is an indie project commercially launched in January 2018. The game came out in early access in December 2014. Initially, Unknown Worlds planned to make a small casual game. But the project grew following the feedback received from players.