It happens to be that I downloaded STALKER from steam because download size is smaller (3gb vs 5 in Galaxy), and them I tried to force Galaxy to recognize the game so the files that were necesary to replace, indeed, get replaced.

However, Galaxy keeps saying that the folder I am pointing out does not have any game ??? It does not even take more than 1 second to say that message. Maybe he dislike the game for being the Steam version??

I wonder if Galaxy search for a REG entry or a specific file ??

There is no official option to import non-GOG games to the client yet. You could try adding it unofficially, but you won't get playtime tracking or any future updates; for those two, you'll have to either install the game via Galaxy or download the standalone installer, install it and let Galaxy do an automatic import.

Galaxy does search for specific registry entries and installations on your PC to auto-import your GOG games. For games that weren't installed on this PC through GOG but copied from another computer (say you installed Undertale on another desktop of yours and copied it to your laptop as the game's folder and not the installer), that's what the import feature is for.

It probably recognizes them by the existence of specific GOG files that are always installed with GOG games. I doubt it can be fooled to replace Steam copies with GOG files to make it a GOG copy though, not at least without owning the game on both clients.

Thanks for the info!

It kinda works. Sadly, I want to enable all the functionallity to Galaxy.

Maybe if I start downloading the game, then I replace the temp files with the already downloaded? It will not work if Galaxy does not check those in order to verify their integrity

The GOG and Steam builds might not be 100% identical to each other, so I wouldn't advise you to mix them up. If you want the full functionality, you'll have to either:

1) Install the game via Galaxy
2) Download the standalone installer which is about 3 GBs, install the game via it and Galaxy should automatically import the game.
3) Wait for GOG to enable playtime tracking for non-GOG games (but you'll still get no updates).

There might be a chance that some games have similar builds across the various stores, but that's not something that you'll find out without experimentation.

Galaxy knows who you are and what you are doing!

Bullshit! Galaxy knows nothing/zilch/zero/nada about me.

Ah, but then you are a sensible chappie and never installed it.

Bloody hell,you found my secret.

I'm not sure but if it's the same conversation I'm thinking of I think we decided the goggame files were the ones needed for importing (and the various Galaxy dlls were for galaxy features in games and not to do with importing them) but it's been a while since I used Galaxy at all and I only loosely follow the development so there may be other things needed...

Edit:
Nevermind, the link Grager gave earlier covers that anyway.

Which option are you using, scan and import? That's the one that looks for GOG specific files to identify which games are present. Try JMich's advice: Navigate to the game in your library in Galaxy, click More -> Manage Installation -> Import Folder.

Galaxy does not import 3rd party games from Steam or other platforms, CD, DVD etc. It only handles GOG games installed either through Galaxy, or via GOG's standalone installers if you use an installer that has had Galaxy support added to it. For GOG games that do not have Galaxy support, you need to do a manual import which should work with most GOG games.

But if you install a game from Steam or elsewhere you're on your own as Galaxy does not support that. Someone created a program that can create Galaxy compatible goginfo files for non-GOG games with which you may be able to get Galaxy to launch a non-GOG game unofficially, or you can create such files yourself by hand as well. Keep in mind that this just allows Galaxy to launch said games, it can not update them or do anything else with them.

If you want STALKER fully working with Galaxy, including getting updates then you need to install the GOG version of the game.

HTH

Thanks to everyone for their answer!

I do have the "goggame-1207660573.info" file, where 1207660573 is STALKER. Either way, Galaxy would not even check the game files via "SCAN AND IMPORT FOLDERS" option, up left in the common GUI.

Nevertheless, Galaxy was able to check the game files via More->Manage Installation->Import Folder and only downloaded those that are different/not exist in the steam version; you pals save me a lot of time! Only 512mb are being downloaded :D

Just to be clear, I do own the game in both platforms, hence my reasons to force Galaxy recognize the game files. Also, I do saved some files -see attached image- that I used to believed are the ones that will convert the Steam version into GOG version; guess I wasnt all clear.

Cheers!