By most accounts, Subnautica is a fantastic game, and it's currently free on the Epic Games Store. But out of the box, it's strictly a singleplayer experience, meaning players are out of luck if they wish to play with a friend. But earlier this month, Subnautica modders released an open source co-op mod for the game. While it's still a little rough around the edges and isn't particularly user friendly, "Nitrox" development appears to be relatively far along, with support for a chat system, a special hud, and syncing players, power systems, buildings, certain vehicles and more. Thanks to PCGamesN for spotting the mod. Check out a video preview of the mod here. This mod is still in its early stages of development, and a public, easy to install version has not been released yet. Those who are keen to try can follow the guide on the wiki. This requires compilation of the mod, and injecting it into Subnautica; not suited for the faint-hearted. Until a stable version is released, this mod is not recommended for casual play. Please be patient as we work to build a great enhancement for the game. How can I contribute? Simply submit a pull request. Feel free to join us in the Subnautica Modders Discord channel. Why the name 'Nitrox'? Nitrox is an alternative air mixture, used by scuba divers, to achieve longer bottom times. As a mod, it will provide a new dimension of gameplay to extend your enjoyment.