I have succeeded at getting the GOG versions of all three Dungeon Siege games, including the Ultima remake mods for Dungeon Siege, to run on Linux using Wine. Getting them to run doesn't require any unusual configuration, but the first two Dungeon Siege games use 4:3 resolutions, and this can be a bit of a pain to set up on modern computers with modern monitors.

I'll split this into three sections since it is long:

General instructions for all three Dungeon Siege games
Ultima remakes
4:3 resolution kluge for NVidia graphics cards (not available yet - due to a forum problem with long posts, someone else needs to post before I can add it)

---- General instructions for all three Dungeon Siege games ----

Disregarding the resolution issue (see the third section), here are the general instructions. This works with all three Dungeon Siege games. I typically install games manually and then add them to Lutris. Using Playonlinux to perform these steps should work too.

First, set up a Wine prefix. I recommend always using a separate Wine prefix for each game in case custom configurations are desired. In the case of Dungeon Siege, using virtual desktops of different sizes to handle the resolution might be desirable, so I do not recommend installing all of the games in the same Wine prefix. I typically use winetricks to set up a prefix. I have Wine 5.0 installed on my system, and I use that to install the game. Afterwards, I configure Lutris to use whichever Wine version I want. I'm using Proton 5.0 for Dungeon Siege 1 and 2 and Wine 5.4 for Dungeon Siege 3. These games don't seem to be picky about Wine version, but antiquated versions might not work well.

WINEPREFIX="{path to wherever you want to put the game}" winetricks win7
WINEPREFIX="{path to wherever you want to put the game}" wine {GOG setup file}

This should install it. Ignore any errors that come up at the end of installation. If you are using Lutris, you can point to the GOG launcher for the executable, and make sure to enter the Wine prefix as well. If you use Playonlinux to follow these steps, it should just work afterwards.

I have also used Killah's patch to get the expansion for Dungeon Siege 1 working. (Don't use this for the Ultima remakes - it might break things.) The expansion for Dungeon Siege 2 is still causing some issues; I think it is registry-related, and it should be possible to solve it. I'll post an update when/if I figure out anything more.

---- Ultima remakes ----

One of the advantages to using Wine over installing these mods on normal Windows is that each one can be installed in its own Wine prefix, allowing the original Dungeon Siege and the two Ultima remakes (and, for that matter, other mods) to be completely independent of each other. I have three Dungeon Siege installations on my computer - one for the original game (with Killah's patch) and the other two for the Ultima remakes (without Killah's patch). I don't know if Windows has a way to have three completely separate installations of the same game, but I suspect that it would be a hassle to set it up given how it uses the registry.

Ultima V Lazarus shouldn't give any problems. Just install Dungeon Siege in a Wine prefix designated for Ultima V Lazarus, download and run the Ultima V Lazarus setup program, and it should work as long as you run the Dungeon Siege executable (point Lutris to DungeonSiege.exe - not the GOG launcher) with the following options (assuming you have installed Lazarus to C:\Lazarus; in Lutris, enter this into the Arguments field in the Game options tab): map_paths=!"c:\Lazarus\resources" res_paths="c:\Lazarus\resources"

Ultima VI Project works essentially the same way, but its installer looks for Dungeon Siege in the Windows registry, and it can only find it automatically if you have installed Dungeon Siege from the original CD. For the GOG version and the Steam version, it is necessary to update the registry. This is true for Windows or Wine, and the fix is exactly the same in either case. To open the registry editor in Wine, execute the following after installing Dungeon Siege in a dedicated Wine prefix for Ultima VI Project but before running the Ultima VI Project setup program.

WINEPREFIX="{path to where you want to install Ultima VI Project}" wine regedit

Then, follow the instructions at this link. (Note that if Ultima V Lazarus ever complains about not finding Dungeon Siege, this might fix it too.)

https://dor-lomin.com/2016/04/30/running-the-ultima-6-project-on-a-steam-edition-of-dungeon-siege/

To summarize, here are the necessary steps. (Note that this is for 64-bit systems. For 32-bit systems, see the link above.)

Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft
Add a key for Microsoft Games here.
Add a key for DungeonSiege (note - no space) under Microsoft Games.
Add a key for 1.0 under DungeonSiege.
In 1.0, add a new string value and name it EXE Path.

Change its value to the path (within the Wine prefix) to the location of the executable, i.e. C:\GOG Games\Dungeon Siege\DungeonSiege.exe or wherever you installed it. Just make sure the path is relative to drive_c in the Wine prefix.

If you can't get there from my summary, check out the link above - this is explained in much greater detail and with exceptional clarity there.

Finally, after Ultima VI Project is installed, the Dungeon Siege executable needs to be run with the appropriate arguments depending on where you have installed it. I find the default location to be a pain since it is deep within the directory structure, so I installed it to C:\U6P. After installing it there, the appropriate arguments to enter into Lutris are map_paths=!"c:\U6P\resources" res_paths="c:\U6P\resources"

Finally, see the next section if you want to display the Ultima remakes in a 4:3 aspect ratio 1024x768 resolution if you have an NVidia graphics card and a typical widescreen monitor. They were designed for this resolution, so using widescreen fixes or displaying them in other resolutions might result in unexpected issues.

(This post is getting too long for the forum, and it won't let me put in another post - it just edits this one and locks up because it is too big. If someone else can post something, I should be able to add the section on resolution as a reply afterwards.)

Nice write-up, eager to read the rest of it.

For the Ultima remakes, I already made drag-and-drop packages to allow the game and both mods to be run independently from each other on the Windows version. You'll find them in the "Install the Ultima 5/6 remakes on the Steam version" section of this document: https: //github.com/GenesisFR/DS1TroubleshootingGuide (remove the space after https)