Here's documentation that Yepoleb wrote
https://gogapidocs.readthedocs.io/en/latest/

Thank you!

Maybe someone else can help...
Got the following error code:

'cren@server:~$ lgogdownloader --download --directory ~/cryptexternal/gog-installer/ --limit-rate 25000
Getting game names (4/4) 92 / 92
terminate called after throwing an instance of 'std::length_error'
what(): basic_string::_M_replace
Aborted (core dumped)'

Running on odroid m1s (ARM single board computer) under Ubuntu Server 20.04 LTS (headless)
Also added to an open ticket on github, but I'll edit my post there if something comes out of here.

What version are you using?
I hope you're not trying to use the version from Ubuntu 20.04 repositories because it is really old (version 3.5 which is from 2019)

Since the output is starting with "Getting game names" it is at most version 3.16.
Version 3.17 had some minor changes to getting game names and details so update to version 3.17 to see if it fixes the issue.

Yeah it was. I added that to my reply on github, but I had to build it. Problem was that 20.04 is stuck on cmake 3.14 (? I think?) So I had to manually update cmake to build lgogdownloader anew. Since then it works. Maybe add a tip/hint/caution NOT to use the distros repos, although I have to admit this is on me for not following the instructions and trying to shortcut via distro repo.
Thanks for the quick response though! :)

On an up-to-date LTS Ubuntu, LGOGDownloader 3.12 is provided, not the 3.5 version.

Here I am not using the 3.12 build but the 3.15 one and it still works nicely (on a Debian Bookworm, backported from when the 3.15 build was provided in Debian Sid), so in my experience you do not need the latest build for basic use.

It required a higher cmake version than that was installed by default. I used this as an opportunity to learn more about Linux as I did a full switch last year and I and I thus far only used rolling releases.

I was able to build it from source and learned about how to properly handle that situation. :)

Hello.

Would it be possible to add 'Good Old Games' as a filtered search for owned games with it in the program?

I don't know how hard it would be to implement or if its already implemented somehow, but I was checking the store to note down what games are being added to the Preservation Program and noticed that it has its own 'tag'/search query: Does Galaxy API support this filtering?
I searched in the SDK docs but couldn't find anything.

Do a tag search for is:good-old-game. Like this.

Hello, thanks for the answer. :)
I meant if it was possible to do something like this in the terminal through lgogdownloader itself, not in the website.

Why were those options removed? Just curious, because I couldn't find anything about it in the closed issues or pull requests.

Because it was kind of a useless feature.
Initially I made it to solve a problem that didn't really need solving.
Getting more details when getting game names from account page for games that were on the list.
The main reason for getting the details earlier was to make --list show dlcs in the output.

The biggest issue with the feature was that the list needed to be updated manually.
The last time I updated the list was 8 years ago.
Well technically I automated most of it but then GOG changed some stuff and I didn't bother updating the scripts I used.

The list wasn't really needed anyway because lgogdownloader already had a feature that could do the same job.
dlc-list was a feature that automated usage of --ignore-dlc-count option by leveraging the blacklist format lgogdownloader uses instead of cli regex or game specific config files.

Unless one used a list they updated themself or used an updated list provided by someone else then they were better off using --ignore-dlc-count ".*" instead of dlc-list for the past 8 years.

Thanks for the detailed answer. And overall for this awesome tool!