1) Set Proton compatability to 7.0-6
2) Install Soulbringer game
3) Run the game once (it will fail)
4) Use terminal and execute this command:

5) Run the game again, set video options in launcher to Software, 800x600 x8 and start the game, then quit once you see the main menu. *
6) Browse installed game files
7) Edit ddraw.ini which is now generated in game root after running the game, in this file:
set maxfps=60
set maxgameticks=60
set minfps=10
set vsync=true

8) Save and close the .ini file
9) Play the game and enjoy.


* you can play around with resolution settings and see which one you like best, once you get the game running all silky smooth.

Interplay, Infogrames and Gremlin Interactive for this gem of a game.
FunkyFr3sh for cnc_ddraw: https://github.com/FunkyFr3sh/cnc-ddraw.
MarceloMarmeloMartelo for leading me to cnc_ddraw as a possible solution.