I've developed a particular affinity for off-line installing.
I enjoy knowing that internet or no...I may still access my (some of) favorite titles etc...,
only there's one caveat to my intaller bliiss and that's that there are a handful of titles that despite my efforts even though GOG continues to monitor off-line install for updates... these are not seen.

In other words Everything I've intalled off-line as you probably know, are still seen in my Installed library, or catagory except some of the major titles. PoE:Deadfire / We Happy Few/ three or four more that will-not be in that Installed list. I'm fine with that except for the fact that they're 'seen' as neeeding to be 'Installed". Hence - not updated - at all.
AoW:Planetfalll is another one by Paradox. If they're not observed as intalled, I cannot request a search for possible update(s). Hope this makes sense.

If you're familiar, and can understand my ravings up there and there's a work around...

any help'd be apppreciated thanks

If I understand it right, you installed them manually by extracting them. So, manually, you should be able to do the same with updates. Extract and replace.

If i didn't understand it right, then i apologise.

Actually I'd not have expected GOG (I assume that you mean Galaxy by that, since everything else is just a fancy website) can monitor offline installs at all. For that to work, it would need a way to know about them. I assume that you're using Galaxy, so you can use the cogwheel in the upper left and "manually add installed games". Maybe you can also "scan for GOG games" and point that to the location you placed the game. It could work if the offline installers add the GOG manifest by which Galaxy detects GOG games. But if you do any of that, then what is the point of using the offline installer in the first place? GOG games installed through Galaxy don't require internet access nor Galaxy to be running, so you can just as well launch them from the executable...?
Or does the webstore send you an email if there's been an update since you last downloaded the game installer? Would be neat, but at least I never got such a mail nor a notification after logging in (though I manage my installs through Galaxy, I've downloaded a select few offliners, but these likely will never get an update, so I wouldn't necessarily know).

ty for your response, and yes:

although...

1. The main game files, and or any dlc / expansion stuff are clearly recognizable

2. The patches? I guess it's easy enough to determine on a good guess which is the most recent patch, therefore which one to take and apply if necessary but the patches are not dated, and there's no time stamp.

3. I don't, and have not had to apply any patches because they're already applied. I've tried, and for the bigger games I usually do. I'll take the last patch down and try it, after all game files are installed, and it'll say that it's update already.

4. Finally, there must be some type of manifest, or telemetry because 95% of the games added using the off-line installers are listed right along side anything that might have been installed/added using Galaxy, under Installed.
I disliked this a great deal at first.
I grumbled to myself about it , before I realize that hey this is great because their maintained by Galaxy too!

Which is what the OPost was all about. A handful of titles that for some reason are not being 'manifested', or simply put aren't being listed as installed, therefore are not eligable for maintainence. Updates.

I've tried adding them manually, and for this user - it's never worked. Not here at GoG, not anyplace.

I'm only now 'investigating' this more or less thoroughly, so I'm sure there are things I haven't tried but for now I'd settle for one person, who's experienced the same.

thanks folks

Ty for speaking to this. I'd hoped to that some of what I answered to Honglath - might speak to what you said to me but I'm not sure it will. Ty none-the-less )

So, I tested a few things and have observed the following:
Most GOG games have two files named "goggame-<some number>.info" and ".hashdb". Some have additional files of that format. The number is the GOG game ID from the store. The .info file is the one by which Galaxy finds installed games when you use the "search for GOG games".
These games have an installer that is made by GOG or for GOG, and probably has mention of GOG in its dialogs somewhere, and that installer seeks out Galaxy installs and updates Galaxys database with the location you install to. This is local and happens even without internet connection.
If you move these games, Galaxy will no longer find them, until you use the above "search for" feature.
I used "Delores-A Thimbleweed Park Mini-Adventure" for the test as it is just 68MB in size.

The games that have no such installer and create no such files are the ones that Galaxy does not easily find. I tested that with "Shadows Awakening". There seems to be a notable difference between offline and online installer. I had SA installed through the offline installer because it would not save, and I'd read the offline install might work (it didn't). But the install did not have the goggame-<number> files, so Galaxy did not find it even if I pointed the search to it.
I was able to make it recognize the game by going to the game in my library, selecting the little "twin slider" icon, then "Manage installation" and then "import folder". That made it recognize the game, but it started an update that pulled 6.28GB (which is nearly the entire games size, which is odd, unless there has been an update meanwhile). After doing so, the game is listed in the "installed" section as if it had been installed through Galaxy in the first place, and after the update ran, the aforementioned "goggame-<number>" files had been added to the folder as well.

So, it seems some offline installers are not "Galaxy-aware", and the resulting install differs greatly from the online installed version, while most install the exact same fileset no matter what, and notify any Galaxy they find. I vaguely remember I did some uninstalling of Galaxy as well when I tried to get SA to save, so it might be that I had uninstalled Galaxy prior to installing via offline installer, which I did not do for Delores. Anyway, the resulting install obviously was severely different from an online install.

I have also made Galaxy accept a Steam install of Tomb Raider: Underworld as its own by means of the goggame-<number>.info file, see
https://www.gog.com/forum/general_beta_gog_galaxy_2.0/can_i_download_the_file_lists_and_manifests_separately

if you care, so it might have worked that way as well for SA. But the "import folder" method is more integral and less hacky, so probably preferrable.

If he has no desire for telemetry, it stands to reason, installing a client was a bad idea. Uninstall galaxy and enjoy your games. Problem solved.

i hope this thread is working out