Hello @cddt, please add PROTON_LOG=1 %command% to the game's launch options and drag and drop the generated $HOME/steam-$APPID.log into the comment box.
Full log attached.
Game works with latest Proton version after converting song data.
PROTON_LOG=1x1 2018-09
Game does not load, reports unknown shader cache type and exits.
Log from ~/.steam/steam/logs/shader_log.txt:
System info: