Drakan: Order of the Flame – Linux/COSMIC Fix
This guide enables music and fixes mouse behavior using Proton Experimental on Wayland.

Requirements:
Steam (add as non-Steam game)
Proton Experimental
Drakan AIO / Community Patch installed

1. Music Setup (DirectMusic)
Run the following command (replace <APPID> with your Steam ID): WINEPREFIX=~/.steam/steam/steamapps/compatdata/<APPID>/pfx winetricks directmusic

2. Configure Overrides
Open winecfg for the prefix and set the following libraries to Native:

dmband, dmime, dmloader, dmstyle, dmsynth, dmusic

Note: Do not override dsound, quartz, or winmm.

3. Finalize & Launch
Refresh Prefix: WINEPREFIX=~/.steam/steam/steamapps/compatdata/<APPID>/pfx wineboot -u

Steam Launch Options: WINEDLLOVERRIDES="dmband,dmime,dmloader,dmstyle,dmsynth,dmusic=native" %command%

Proton: Ensure the game is set to Proton Experimental.

Let me know if this worked for you!

I don't have Linux but thanks very much for posting this information which may well help others. I keep hoping that this game will come to GOG someday.