By default, running this usually makes it crash before the title screen. Using GE-Proton gets you in-game but with abysmal framerate. You can use the much easier way and go with the Luxtorpeda/OpenLara solution but that’s not how I wanted to play TR1 personally. This way will install Tomb1Main (now known as TR1X). It’s easier to get this set up on a PC and then transfer the folder to your Deck, but for this guide, I’ll keep it Deck only. There might be some uneccesary steps here that a more experience Linux user won’t need but this is what worked for me. :)

You need the following:

• the Windows zip file from TR1X’s Github page (https://github.com/LostArtefacts/TR1X)
• the TombATI installer (https://www.glidos.net/tombati.html)
• PowerISO and Protontricks from the Discover Store

TOMB RAIDER 1 GUIDE

• Make a clean Steam install of Tomb Raider I
• Add TombATI.exe to Steam, run it through GE-Proton
• Install it to somewhere on your desktop, it will make a TombATI folder. You won’t be able to do the “copy from Steam” part, but that’s okay.
• Extract the TR1X zip, throw it into the TombATI folder
• Navigate to the Tomb Raider (I) Steam folder, throw all the files within TombATI into that folder
• IMPORTANT: Steam Deck differentiates between capitalized and uncapitalized letters in folder names so make sure everything is in one folder instead of having “SHADERS” and “shaders” folders
• now find “GAME.GOG” in the Tomb Raider folder. Rename it to “GAME.ISO” and open it using PowerISO
• Extract the DATA, MUSIC and FMV folders, put the files in the Tomb Raider folder (this is the step you couldn’t do with the TombATI installer)
• rename dosbox.exe to dosbox_original.exe.
• make a copy of TR1X.exe and rename it to dosbox.exe
• Tomb Raider 1 should be ready to go

UNFINISHED BUSINESS GUIDE (AND CONFIGURING TR1/TRUB)

There might be an easier way of getting UB running but I’m a Linux noob so this is what worked for me. I recommend doing this after you’re done with TR1 but you might want to configure the game as well. This will provide a way to do so but you don’t actually need it for configuring, you can go to the cfg folder in the TR folder and open “TR1X.json5”.

• make a copy of that new dosbox.exe you made and rename it dosbox_TR1.exe or something.
• make a copy of TR1X_ConfigTool.exe and name it dosbox.exe
• open up Protontricks, navigate to Tomb Raider I, hit “select the default wineprefix”, then “install a Windows DLL or component”, scroll down and find “dotnetdesktop6”, and install it (you might need to run the other dotnet installers listed but just dotnetdesktop6 should work
• run Tomb Raider and you should see a window with lots of gameplay options to tweak. More importantly, you’ll see the “launch Unfinished Business” button at the bottom. Click that and boom you’re running UB!
• You can also tweak the game to maybe get a more vanilla experience like removing enemy HP bars, underwater rolls, and Lara’s braid, it's up to you. As mentioned before, you can do all this in the “TR1X.json5” config file
• and of course, you can just rename the “dosbox_TR1.exe” back to dosbox.exe to get TR1 back.

Hopefully you're good to go from here! and hopefully, the Tomb Raider remaster will make all this unneccesary! :D