Subnautica has sold over 5 million copies, as revealed by Unknown Worlds’ founder Ryan Cleveland in an interview with GamesIndustry International.

The figures take into account every version of the game launched since early access in December 2014, with the title that entered a full release state only in January 2018, four years later.

The total currently sits at 5.23 million copies, which cover PC on Steam and Epic Games Store, Xbox One, and PlayStation 4.

It’s worth noting that these numbers don’t include free downloads. Subnautica has been available for free for two weeks on Epic Games Store last year, and in that timeframe, it managed to reach an additional 4.5 million downloads.

“The free games have been a huge success, much bigger than expected,” Epic Games’ founder and CEO Tim Sweeney told GamesIndustry commenting the strong figure. “We’ve gone around working with game developers and paid them for the opportunity to release their games for free for two weeks. That’s brought in a huge number of new gamers.”

Subnautica offers a unique, often terrifying, underwater-based survival experience, unlike any other. With massive biomes to explore, creatures to encounter, and threats to be faced, it can feel like an eternal game.

There are plans already in place for a sequel, Below Zero, which is currently available, again, as an early access title on Steam. It launched in January last year and has yet to be completed but has been able to get a “very positive” reception on Valve’s platform.