Apart from the problematic intro video and some effort required to get the music working, the experience is satisfactory overall.
TO FIX THE MUSIC NOT PLAYING:
protontricks - install "directmusic" and "dsdmo", set "sound=alsa"
copy all of the .dls files from
/steamapps/common/Cultures Northland/DataX/DM2/
to
/steamapps/compatdata/351860/pfx/drive_c/windows/syswow64/drivers/ #(I did it for one folder above too, just in case )
I used a tutorial from here:
https://steamcommunity.com/app/266210/discussions/0/1732090362043130890/
and repeated the steps - maybe not all of them are necessary, but it did the trick for me - the music is working!!!
there are still problems with the intro movie
Works fine, intro video plays.
Game has no window mode
Played with Proton 6.3-8
Fully playable on Proton 3.7-8, all other versions have screen lag whenever the mouse is moved, and crackling sound.
The game music doesn't play, but sound otherwise works.
Intro videos do not play, you have to ESC to skip it otherwise it will hang on a black screen indefinitely.
Mouse / Screen lag makes the game unplayable
Mouse causes game screen update to lag inexplicably, making it unplayable.
Moving the mouse causes stuttering, lag, and freezing of the game screen.
Works fine on Proton 5.0.7.
Don't show start video. :(
Game runs fine, except for having a very tiny cursor. However, it crashes when I change resolution in the settings
Works out of box. Only one minor issue is - missing intro (video not playing). All other work fine. Platinum rate.
Opening video doesn't play
video not playing