I launched the game in proton experimental and I did the same thing as user Tim Co©K dit (thanks, by the way) and I'll just copy and paste his procedure and call it a day, because that's the only things I've to do to make the game works on Deck (with minor visual glitches, face transparency for exemple) :

Game crashes because of missing file "shine_glowing.wmv". This file is being user for UI modal. So to fix it:

You need to go in desktop mode on your Deck, then go to Dolphin > Steamapps > Common > Arcania :

1- Go to folder "Data/Video" 2- Make a copy of a small file like "B_ShadowBeast.wmv" to "B_ShadowBeast (Copy).wmv" 3- Rename the "B_ShadowBeast (Copy).wmv" to "shine_glowing.wmv" 4- Play game

And then, you can enjoy the worst Gothic game, which is still a fine game that deserve a try.