


Config file path
/home/deck/.local/share/Steam/steamapps/compatdata/1689910/pfx/drive_c/users/steamuser/AppData/Roaming/Shiravune/DOUKYUUSEI/Save/config.xml
Changes
<Screen>
...
<Window>
<Width>1280</Width>
<Height>720</Height>
...
</Window>
<Status>1</Status>
...
</Screen>
Install the game through Steam game mode, as usual.
Run the game once to generate config file, then exit the game. Then, apply changes to the file.
I also recommend disabling Steam Cloud for this game, as this config might get synced between your machines, if you change game video settings on your PC the change will propagate to your Steam Deck.

Start the game first in desktop mode, move mouse to the top of the window to open game system menu.
- Window > Revert to original size
- Settings > Window settings > Display to match display resolution without scaling
- Window size > 1280x720. This should disable the system menu focus steal in game mode.
Selecting Proton 9.0 should work for videos without additional codec install.
Default configuration has system menu popup when mouse is at the top of the window, which breaks gamemode. Can be disabled by configuring the window mode in desktop configuration.
Run winecfg to enable "Emulate a virtual desktop" and set "Desktop size" to 1280x800. Install lavfilters to continue playing
Enable "Emulate a virtual desktop" to fix the black screen after starting in Gaming Mode. Install lavfilters to play the animation and contiune to play.
protontricks 1689910 lavfilters
gamemode starts with black screen, it needs to press Alt + enter to fix it
Installed lav filters for the opening
Mapped back butttons L4 and R4 to mouse keys & mapped one of the back keys to hit ALT+Enter to change into windowed mode
40hz refresh rate
Game starts with a black screen, press ALT+Enter twice to get the game to show an image.
Installing the patch is just drag n drop like on Windows.

audio loopt
black screen when started from steamdeck gui
protontricks flags: ffdshow quartz wmp11 d3dx9 d3dcompiler_43 d3dcompiler_47 vcrun2003 vcrun2005 vcrun2008 vcrun2010 vcrun2012 vcrun2013 vcrun2015 vcrun2017 vcrun2019
The bgm loops after 5 seconds