This guide helps you install the Nitrox multiplayer mod for Subnautica on Linux using Steam.

• Nitrox lets you play Subnautica with friends
• You can explore the ocean together, build bases and survive as a team
• This guide makes installing Nitrox easy on Linux

• Linux (Ubuntu, Fedora, etc.)
• Steam
• Subnautica installed on Steam
• Internet connection

Clone the repository or download the files locally, in this directory :

1. Open config.sh and set your Steam folder path
2. In a terminal, run ./install.sh setup to:
   • Download and install Nitrox
   • Configure Steam launch options
   • Add NitroxLauncher to Steam
   • Store the Nitrox patch
3. Run ./install.sh patch to activate the mod
4. Launch Subnautica and play with friends!

You can do everything manually, the script is just a helper to guide you through the process and automate some steps.

Install Subnautica from Steam.

Download Nitrox from github : https://github.com/SubnauticaNitrox/Nitrox/releases/tag/1.7.1.0

The zip file is what we need.

Unzip the folder into your Subnautica prefix, at the root of the C: drive : $STEAM_DIR/steamapps/compatdata/264710/pfx/drive_c/Nitrox

264710 is the Subnautica Game ID on Steam.

• open your Steam library
• right click on Subnautica in your library
• click on Properties
• in Set Launch Options, type -nitrox C:\Nitrox
• open the Betas tab
• on the dropdown, select legacy - Public legacy builds

Add to Steam:

• open your Steam library
• click on Add a game on the bottom left corner
• select Add a non-steam game
• click on Browse... on the bottom left corner
• select NitroxLauncher.exe ; should be in $STEAM_DIR/steamapps/compatdata/264710/pfx/drive_c/Nitrox

NitroxLauncher should be added to your library.

Configure NitroxLauncher:

• right click on NitroxLauncher in your library
• click on Properties
• open the Compatibility tab
• enable Force the use of specific Steam Play compatibility tool
• on the dropdown menu, select Proton 8.0 or the latest version
• close the settings window

You should be able to launch NitroxLauncher from Steam. It can take a while to start, please be patient.

When NitroxLauncher launches the game, it will patch the file Assembly-CSharp.dll in the game folder. The location of the file is $STEAM_DIR/steamapps/common/Subnautica/Subnautica_Data/Managed/Assembly-CSharp.dll

We need to :

• launch NitroxLauncher from Steam
• click on the 'PLAY MULTIPLAYER' button
• a small blue popup should show up at the bottom with 'Launching Subnautica...'
• copy the patched file somewhere else
• close NitroxLauncher

We are good to go!

To launch the Nitrox server :

• open NitroxLauncher from Steam
• go to the 'SERVER' tab
• click on the 'START SERVER' button

To launch Subnautica with Nitrox :

• replace the file Assembly-CSharp.dll in the game folder with the patched file you copied earlier
• launch Subnautica from Steam

The patch stays applied, but can be overriden by Steam (updates, etc).