You should really try again if you haven't tried in the past month or two. Steam recently released proton 5.13 into the list of proton releases, and since then,

You should really try again if you haven't tried in the past month or two. Steam recently released proton 5.13 into the list of proton releases, and since then, a great percent of games that didn't work in earlier 5.* releases have started working. Including Doom Eternal and now this game. Guessing they were prepping for this game.