Neither the "native" nor Windows version work with Proton. "Native": As another commenter already said, "native" means "the Win version in a package with some Wine libraries and scripts". The game was released in 2005, so its Wine libraries must be ancient. No wonder it fails nowadays. Win: At launch a terminal and a blue window pop up. I have to enter a serial number in the blue window, but Steam does not provide such number. Another commenter fixed it by extracting some registry values from a file of the installation folder and adding those manually to the registry. Sadly, it did not work for me. Or I did it wrong. :-( Workaround: After Proton failed (for me) I got the game from GOG. That Linux version also fails, but that Win version works with Wine. (For me, at least.) No serial number needed. Another issue: The resolution isn't scaled on Linux. So if you're using HiRes, a part of the screen is black. (At least with the GOG version.) If you run the game on Windows the resolution gets scaled.