I recently bought Doom (1993) from GOG. They do not offer native linux support, but Doom is open source given the WAD you can play it on just about anything. Here is how to extract the WAD:

1. Download innoextract. This is available in every major linux distro's package manager.
2. Download the setup.exe from GOG.
3. Run innoextract setup.exe. Change the name of the file as needed. I recommend creating a folder and extract it in there because it does not create a separate folder.
4. There should be a file called DOOM.WAD. That is the game data.
5. Additionally there are a few other files like manuals and the Doom Bible.

And there is the data needed to play the game. Additionally we can see dosbox is bundled which I thought was kind of funny.