PROTON_USE_WINED3D11=1 %command%
The game was crashing with some "Win32 function Graphics_DisplayM.cpp" error. Adding PROTON_USE_WINED3D11=1 %command%
was enough to run the game.
Works almost flawlessly out of the box.
After starting the game in fullscreen it's not in the foreground, but alt-tabbing to steam and back to the game fixes the issue.
Very Minor Issue. The game is set to Windowed as default. The cursor can't fully reach the right side of the screen as if part of the right screen is cutoff. Switching to Fullscreen in Options fixes this issue.
Other than that one very minor issue that the Developer can easily fix by making "Full Screen" the default for Steam Deck, the game runs fine right out of the gate. Default Mouse controls get the job done.
If the Developer can just address that one issue, then this would get the "Great On Deck" seal of approval.