


unset LC_ALL && %command%
Requires setting launch options + custom proton version. Otherwise, menu audio would continously play even after selecting a game with no ability to mute it. Once applied, game runs fine.
PROTON_SET_GAME_DRIVE=1 %command% unset LC_ALL && %command%
Update to my previous report - adding the launch option "unset LC_ALL && %command%" fixed all the problems with saving.
The game had some issues like other M2 Collections in the past, but this seems fixed. Game runs flawless on Steam Deck.
Needs tweaking for fullscreen dual monitor support; also refuses to recognise disc space for saving option changes. Game itself runs though
Steam Tinker Launcher, Gamescope
Fullscreen Dual Monitor support had to be forced through external terminal command of xdotool: "xdotool getactivewindow windowsize 100% 100%". Also needed to the hide the GNOME titlebar with "xprop -format _MOTIF_WM_HINTS 32c -set _MOTIF_WM_HINTS 2". Added both of these as keychord shortcuts
Ongoing problem with game reporting "Insufficient space on disk" any time an option is changed through the menu, which puts the game into an inescapable pop-up error window loop.
However, on forcing the game to quit and reloading, any settings changed last time have actually been applied and retained.
Still searching for a fix for this, "PROTON_SET_GAME_DRIVE=1 %command%" as recommended on similar game reports isn't working.