err:mscoree:CLRRuntimeInfo_GetRuntimeHost Wine Mono is not installed in the log points towards #18.
Just want to add that this is currently still an issue.
There is a solution on protondb that is to run the below on the command line:
WINEPREFIX=%pathToSteamLibrary%/Steam/steamapps/compatdata/258010/pfx winetricks xna40 dotnet40 gdiplus
It would be nice if this was resolved so it worked natively on the install on the steamdeck.
Looks like it needs Microsoft.Xna.Framework.Media.MediaLibrary
WINEPREFIX=%pathToSteamLibrary%/Steam/steamapps/compatdata/258010/pfxx1 2025-07PROTON_LOGx1 2019-01
Compatibility Report
System Information
I confirm:
PROTON_LOG here
Symptoms
Game does not start at all