Unknown Worlds Entertainment is celebrating a significant milestone with its title Subnautica. According to the company’s founder, Charlie Cleveland, the game has sold millions worldwide.

Cleveland commented on the success of Subnautica in a recent interview.

“Subnautica is an underwater adventure game set on an alien ocean planet. A massive, open-world full of wonder and peril awaits you!” Says the Steam page. Players can expect an exploratory adventure, “You have crash-landed on an alien ocean world, and the only way to go is down. Subnautica’s oceans range from sun-drenched shallow coral reefs to treacherous deep-sea trenches, lava fields, and bio-luminescent underwater rivers. Manage your oxygen supply as you explore kelp forests, plateaus, reefs, and winding cave systems. The water teems with life: Some of it helpful, much of it harmful.”

Subnautica excels in allowing players to explore open-world environments, plus craft tools to help them research the ocean depths. Players can also create unique underwater bases to call home.

Cleveland specified that the exact number of games sales was 5.23 million across PC on Steam and Epic Games Store, PlayStation 4, and the Xbox One. He didn’t specify where the game was most popular, but overall, gamers across multiple platforms are continuing to enjoy the game after its release.

The sequel to Subnautica, Below Zero, is currently in Early Access. The game is set in the icy world of Planet 4546B, where the player is studying alien artifacts. Players can explore caves, snow-covered peaks, plus the ocean.

The primary goal of the sequel is to understand who the aliens were and why they decided to visit this specific planet. Since the game is still in early access, there’s likely to be several changes before its final release. The official Steam page states the release date is on January 30th. Currently, only the PC release has been confirmed, but the team is working on releasing it on the PlayStation 4 and Xbox One, similar to the original game.

Subnautica was available for free during a two week period on the Epic Games Store in early 2019, where it had 4.5 million downloads. It’s not uncommon for some players to love a game so much that they buy it to support the developer create future titles.

Subnautica is available now on PC, Mac, PlayStation 4, and Xbox One.