The ability to download and store the offline installers on your HDD, etc. is THE advantage, that GOG has over Steam.

You only have to DL them again, if you delete them after installation (and why would you do that?), or if an update gets released (and updates would have to be downloaded on Steam, too - if you want your game(s) to be,...well...up-to-date).

Most games normally get an offline installers for patches so if one is made for the game you can just download that, then you install the base game offline installers followed by the update installer.

If you made the error of using Galaxy to install your games, you can not use said installed games to re-generate the DRM-free installers.

There isn't a built-in system to package up your installation to turn it into a backup locally, no. You could do it yourself using a zip/tar/7zip archive or similar, but that doesn't work for all (or many tbh) game installations (because of dependencies and installed registry entries etc, the "roots" of an installation). Re-downloading, but this time the offline installers, are the best bet.

If you mean copy the installation folder, then it's better to download the offline installer to make sure it install everything the game needs to launch without problem

I'd heard in the past, the steam client would download an installer exe, and if you interrupted it at the right time you could copy said installer as a single exe file (like plants vs zombies) before it was deleted.

Though i'm sure they don't do that anymore.

I am not sure what you mean by "steam like function."

But of course you can backup games you've already downloaded.

Just copy & paste the offline installer files to the new location where you want the new backups to be saved, and then you will have created new backups of them.

With Steam you can tell it to make a backup of a game and it verifies and uses the current installation files on your system (plus a tad more download) to create backup packages you can store.

So the OP is asking whether Galaxy does something similar or will he have to download pre-made offline installers to have a backup/installer package.

I had the impression with Steam, you could go to 'offline mode' and then detach yourself from the internet. Then if you made a full raw drive backup you could store the installed games as they are on your machine for future use.. maybe...

That might be possible, I have no idea. But that's not the official backup system Steam offers to its customers.

Well it isn't too hard to copy a game install folder. You can even zip it up and compress it if you want to save storage space. If you use 7-Zip for instance you can even turn it into a self extracting installer.

It is a gamble though, as there might be elements missing, that are stored outside the game folder or required when installing on a different OS, even registry entries in some cases. Most of the time though, you should be okay.

GOG though, should never have provided the all-in-one download install option that Galaxy uses. It runs counter to DRM-Free, which is all about backing up your games. Until you do that, your game isn't truly DRM-Free.

GOG could have set Galaxy to download the Offline Installers and then automate installing those, leaving the Offline Installers available to relocate and backup. That's what they should have done.

Anyway, I serious recommend you re-download to get the proper Offline Installers, and back them up to more than one drive. It is well worth the pain you may feel in doing so, especially as you paid for those games, to own them.

Thanks everyone. I will download the offline installers and get the games again. I want to have a DRM free local copy of everything in case GOG isn't available or I move to some country that gets banned from playing games for political reasons.

Unless it's a RPGMaker game, or Renpy (both unlikely), yeah it is a gamble.

Though i see a lot of Unity and Unreal games that also work fine extract and run, assuming the dependencies are installed.

Probably the more annoying thing with the installers is that you can't modify them, so you can't remove garbage present in a game, or optimize images to be smaller.

True, but you can always keep a copy of the installers AND package up your altered files as a kind of overwrite patch to store with it (I'd even write a batch or make a self-extractor to automate the overwrite extraction). It's clunky and wasteful, but it's the best we can do, really.