The German Installer works, I've tested it - with Galaxy closed and GalaxyCommunication.Exe killed in Task Manager. File seize is 326.682 KB.

Thanks for the verification, obviously GOG forgot to add the files to the executable. Hopefully it'll be rectified soon.

Yep, I can confirm this. Just tested it myself.

French too, at 321mb (after fix)

Other language, except english, the offline setup at 250mb (i don't know if they work or not)

It's just english's setup who as 200mb
There is clearly a problem in the files

For Dungeon siege 3, I just installed both the game & dlc from from the offline installers I downloaded on the day I bought it. I'm getting the same issue with the dlc missing. For some unknown reason there is also a steam_api.dll and Steam_appid.txt file in the GOG install. Surely that is a screw-up too.

I also did a comparison between my Steam copy of the game and the GOG version. There are definitely files missing, however just dropping in my dlc directory from the steam version doesn't make the dlc work properly so possibly there is a registry or config file change required too.

*edit* I'm using the English language versions of the offline installers download via galaxy. Both the base game & dlc are listed as version 1.0 on GOG.

One thing to remember if you are trying to test if the offline installer is working don't forget to completely shutdown galaxy before you install. With Galaxy 1(I assume the same happens with galaxy 2), if the installer spotted galaxy was running it would partially configure itself with that and do things like make the start-up shortcuts automatically start galaxy running instead of running the program file directly.

I've never paid Galaxy that much attention w/ how it works (even though I've had GOG Galaxy 2 since the Beta), but...since some of y'all are having issues w/ DS3 DLC's...

...is there an also offline mode for GOG Galaxy?

Might be a good idea if there was one, just in case they need to find a way to make the game and especially its DLC's work, just in case the game needs the Steam files there so that GOG Galaxy can re-interpret the DLC's and make them actually work.

There is no such thing as an offline mode for Galaxy. It's originally was just as a launcher/back-up file downloader and is supposed to be optional. It was updated to allow for some games that needed additional features to let multiplayer modes operate but since it is not like uplay or origin or steam which use DRM features, there couldn't be an offline mode. Essentially offline mode for Galaxy is just shutting down galaxy.

With dungeon siege 3 it's clear they managed to mess things up when they put together the offline installers. In the case of the steam version of dungeon siege 3 it will still show the dlc even if steam is offline so fundamentally it isn't a game that required online servers to check for entitlement. The most realistic explanation is someone probably put the wrong files in the wrong folders when they built the offline installers.

If they (GOG) have been made aware of the problem via their tech support, then they will be able to sort it out, test it and update it. Sometimes mistakes happen and I don't think there was any malicious intent on the part of GOG, merely an unfortunate accident that was spotted by ordinary users instead of their release team.

Well I just tried the Galaxy version, And I get same issue, as the offline one, DLC not registering.
Issue seems to be one of game not recognising the DLC is installed, As I have all the same files as Steam DLC.
So I'm not convinced it's anything to do with GOG, so much as Square Enix doing a copy paste of Steam files for game/DLC.
Maybe that causes those with the Steam, and GOG releases to not get the GOG version registered, because Steam has already registered the DLC.

See manifest.xml content on GOG DLC, it is a Steam File.
Dungeon Siege III (GOG)\DLC\DLC_1\manifest.xml
<content>
<string_table>dlc_6.std</string_table>
<item>
<resource>dlc_1</resource>
<name>101755</name>
<text>101756</text>
<dlc_id>6</dlc_id>
<mount_priority>0</mount_priority>
<compatibility_mask>1</compatibility_mask>
<steam_appid>39270</steam_appid>
</item>
</content>

Also in base game.
Dungeon Siege III (GOG)\Steam_API.dll
Dungeon Siege III (GOG)\Steam_AppID.txt

I'm thinking it may be just those of us those with both versions, and both containing Steam files, it's messing up the DLC recognition on GOG version, by registering on Steam instead.

I have already the original 2 games with their expansions so I bought this for dungeon siege 3. The game is refusing to install no matter what method I use. I'll place a ticket.

The updated offline installers which allows the game to access the DLC have now been put up and ready to download via the game library page :) It does seem though that you also have to re-download the main game again too.