A little bit of help in organization and presentation goes a long way in helping those of us not able to focus well.

I use offline installers for anything not being actively patched, but I download them through Galaxy because it's easier. If a game is new and getting frequent patches, I play it through Galaxy as well.

Mmmm not sure why so many are saying Offline Installers, when what they really mean is Browser Link downloading, which of course downloads the offline installers, as do the majority of the programs mentioned in the first post.

Of course, with a browser link download there is no verification checking, no MD5 checksum to ensure your download is okay. There is also no queuing, resuming or throttling.

If you are downloading, then installing and playing, then no biggie, as you are checking by doing that. But if you are downloading to archive, then that's a different matter, especially with large files, as you should be checking that what you are backing up is okay.

GOG don't openly provide MD5, but some of the programs in the first post do access the MD5 that GOG provide, and so verify their downloads ... and really that is the whole point of using them, along with queuing and resume and throttling.

There is another way to verify browser downloads, if you don't mind skipping the other benefits of a downloader. GOG use InnoSetup to create their Windows installer files. They can be checked using the free InnoExtract, which even has special parameters for GOG installers. But be warned, it is slow, chiefly because it is using internal MD5 values to check every file inside the EXE. Programs like gogrepo.py and the new gogcli, check the MD5 of the EXE download itself, which is very much quicker.

P.S. You can also get the Offline Installers as an option through Galaxy.

I have uninstalled Galaxy 2 recently and I'm back to installers at least for a while. The unofficial GOG clients are new to me but I will probably check them out before going back to Galaxy.
Also happy to see that there is MiniGalaxy for Linux.

Always wondered how do those programs check that. It must be listed somewhere, right? So it should be accessible even without using them.

GoGRepo.

I'm going to swear on my new idea of GOG making their own equivalent to RPMs and DeltaRPMs, though. It has an initial startup cost, but it would improve GOG for bothoffline installers and galaxy users, as well as gog support staff (when it finally works, anyway). After spending so much time thinking about it, i've even considered making my own spin on it. Maybe drop my source at gog as some kind of hint.

I download the offline installers with a browser and launch any installed games from Total Commander. I don't do multiplayer or achievements.

I've found that the MD5s for the .bin files are actually stored in the .exe file. Search for a "gogcrcstring". But I haven't figured out where the one for the .exe itself is.

use double commander , same as total commander just more modern

If you give me a link with an article, or something, showing what DC does better than TC, then maybe I will. More modern doesn't mean better, for me at least.

it does everything what tc can do + free GPL license open source and multiplatform

I use gogrepoc to back up offline installers:
- regular update (takes a few minutes): whenever an update flag appears in my account.
- full update (takes a few hours): once a month or so, for games/files that GOG fails to indicate as updated.

When installing a game to play, I always install from my backups, never downloading from GOG.

I do not use any kind of "all-in-one" game client. I actually dislike all of these Steam clones, no exception.

To download my games, I use:
- LGOGDownloader for GOG games
- hb-downloader for Humble Bundle games
- BetaRaysʼ automatic-game-downloaders for itch.io games
All of these are called every night on my server to get all updated installers from the last 24 hours.

Then to install the games I use ./play.it (obviously).

Finally, I launch my games from whatever I have at hand, be it an opened console or any applications menu. I do not use some kind of game-specific launcher (what would be the point?).

You would have to do an XML type query of a GOG server database to get the MD5 for the EXE, and as you can probably imagine that is hidden below layers of security etc. You use the GOG SDK to do that.

As for the MD5 values in the EXE file for internal content of the EXE and any associated BIN files, that is what InnoExtract can read and then use to check that the internal content (files) are not corrupt. As you might imagine, it is a very slow process, when some BIN files contain thousands of files.

The EXE and BIN files are container files, much like a ZIP file. They also have their own MD5 value, which is all Galaxy and other party programs check, using the SDK to retrieve the values from the GOG online database. They just check that the download wasn't corrupted, whereas InnoExtract (and the GOG installer when you install) check for internal corruption created at the GOG end.

A program like gogrepo.py and the new gogcli, can build up a local database on a user's computer, called a manifest. If GOG replace files though with updates, you need to re-query GOG for the new MD5 etc values.

On Windows, rarely Playnite (although I use Playnite for IndieGala, mostly). Usually, I just install the drm free installers and link the installed games to Winlaunch (which is similar to OSX's launchpad). It also helps to not cluster my desktop or have to navigate a maze of folders and files
On Ubuntu, I do the same as in Windows with Winlaunch, but using the default launchpad instead. And if the game doesn't get linked there automatically, I add it there through the Alacarte app/tool (which can be downloaded from the terminal)