OpenMW is the best way to play Morrowind on modern systems, so here's your full guide to getting it installed on Linux / SteamOS and Steam Deck.
For SteamOS / Steam Deck, these instructions assume you are in Desktop Mode. We'll also assume in general you're using Steam for the guide for now. These instructions will work on any version of Linux that has access to Flatpak. We may add GOG instructions later.
Option 1) Flathub / Flatpak
Before starting this option, be sure to install Morrowind in Steam first onto your main drive.
Starting off with what might be the simplest option. You can install OpenMW via Flathub, which is available via the Discover app for KDE Plasma / SteamOS. Or Software on GNOME.
Important note: for any time OpenMW updates, you will need to go back into Discover to run the updates (this applies to all Flatpak apps / games installed).
Or, via terminal to install it:
flatpak install flathub org.openmw.OpenMW
Once installed, it will show up in your application launcher. That's the "Start Menu", for those of you more familiar with Windows terms.
With your first load, you will need to then supply it with the version of Morrowind you have installed. Click "Run Installation Wizard" and it will walk you through the steps to find your downloaded version of Morrowind.
You'll want to select "Existing Installation", then hit "Next". It likely won't auto-detect where it's installed on a Linux system, so for this next screen just hit Browse. Then you can manually direct it to where you have Morrowind installed.
Since the main Steam folder is hidden, you'll need to unhide the contents of your Home folder. You can do CTRL+H (usually) to unhide files and folders, or in the KDE Plasma file picker in the top left is the settings button, where you can select "Show Hidden Files".
Then you can find and open the ".steam" folder and go through to this location:
/.steam/root/steamapps/common/Morrowind/Data Files/
This is where the needed "Morrowind.esm" Morrowind master file will be to pick.
Select the file, click "Open" and then you're done and OpenMW will be able to use all the data files needed from your Morrowind install. Now follow the rest of the instructions (you can just keep hitting Next until it's done).
Finally, you'll get to the launcher that has everything needed.
Here you can just hit "Launch Open" and you're good to go.
To make it easier to run in future if you're on SteamOS / Steam Deck, you can add this OpenMW install into Steam.
It will then appear in your Steam Library under the Non-Steam section in SteamOS Gaming Mode.
For all other Linux distributions, you can add OpenMW via the Add a Game option in the bottom left of Steam:
Then scroll down to select the OpenMW Launcher:
Click "Add Selected Programs" and it will appear in your Steam list.
Option 2) Luxtorpeda
For this step, you don't need to have Morrowind installed yet. We'll do that at the end.
Another option you could use, that you might prefer, is Luxtorpeda. This tool allows you to download Native Linux versions of games on Steam using external sources, like OpenMW for Morrowind. Luxtorpeda supports various games.
Starting steps are similar to option 1. Except we'll be grabbing ProtonUp-Qt to help with this from our software store like Discover on KDE Plasma / SteamOS.
Or via terminal if you prefer:
flatpak install flathub net.davidotek.pupgui2
Once installed, you can launch ProtonUp-Qt from the application launcher. That's the "Start Menu", for those of you more familiar with Windows terms.
Inside ProtonUp-Qt, we're going to select "Add version" and on the next screen, the drop-down box at the top you're going to click and select Luxtorpeda.
Tap "Install", wait a while and let it set it up for you. Then once done, you can close ProtonUp-Qt and you'll also need to close and reopen Steam so that it picks up Luxtorpeda.
Once you have Steam open again, you can go into the Properties menu for Morrowind, select the Compatibility menu, tick the box and select Luxtorpeda.
Once selected, you can close the properties menu and install Morrowind. Then, when you go to launch it, Luxtorpeda will do the magic for you by acquiring and setting up OpenMW for Morrowind. Keeping it all nice and neat directly in your Steam library to launch it direct.
First you'll get the Luxtorpeda engine selection, just pick the top one, OpenMW and go through it and it will install it for you. You don't need to mess with any manual hunting of files with this method.
Once it's downloaded the bits it needs, it will launch it for you.
Each time you go to launch it if you have it installed with Luxtorpeda, it will ask which engine to pick and you can just again pick the top one of OpenMW each time and then it will load like the above shot. However, if you need to edit some other settings, you can select "OpenMW Launcher" to get it to load that first.
If any steps are unclear or if anything needs updating, be sure to leave a comment and we'll get to it.