All my games on Heroic have the option to enable Feral Game Mode except for the one native linux game I own which happens to be Slime Rancher. I've tried to manually add the launch option to the game in Heroic like you would in Steam (gamemoderun %command%) and even tried plain (gamemoderun). I've searched on this channel, the website, as well as google to find out if I was doing something wrong and can't seem to find anything as silly as it is. I was able to add the game to Steam and use it's launch options (gamemoderun %command%) as a workaround but I'd prefer to keep Heroic games in Heroic if possible. I've added my Heroic log as a just in case although it doesn't seem too helpful.