Game would not open without proton. Upon booting up the game, if I do not immediately skip the opening credits (via hitting space bar or something), the game will freeze my entire computer and I'll need to force a restart. Skipping the opening credits fast enough (ie. hitting space as soon as I see the first logo fade in) allows the game to load normally. Have not played for long enough on linux to be able to tell if the game remains stable, but I can access my save files and whatnot just fine.