I was able to almost fully reverse engineer the protocol types, so now they're very close to usable. I've decided to rename the repository to gog_protocols because it's no longer just a dump. The new URL is now https://github.com/Yepoleb/gog_protocols

Thank you very much for this!

I recently started to play around with the API, the very humble results can be found on Github:
User: NicoVIII
Repository: Andromeda-for-GOG
(link: https://github.com/NicoVIII/Andromeda-for-GOG )

Are there Galaxy alternative projects I don't know of and I didn't find?

https://www.gog.com/forum/general/comet_galaxy_client_for_linux
It is focused on multiplayer for now.

Ah, cool! I only looked on github, should have searched the forum I guess... Thanks!

Is there an equivalent to getFilteredProducts using the Galaxy API ? I assume there must be since Galaxy displays different data about owned games than the website does but I can't see anything in the docs.

Edit- Also is there a way to programmatically find the galaxy Catalog I'd given a web Game id ?

For the second question some game eg Bards Tale IV have a web game id that isn't equivalent to their galaxy API id , so you can't just substitute the web id into the Galaxy API product info link (you get a 404). I'm wondering if there's a known way to generate the Galaxy API product link from the information available (tho this might be an issue of me using www.gog.com/accounts instead of embed.gog.com , perhaps it uses the different id).

I'll generate a report tonight so I have some better data.

The Galaxy ID should be equal to the one listed in getFilteredProducts. You can link then one way to the store pages by following the store link.

Not sure if's some weird inconsistency caused by me mucking around but at least right now for me:

(this is for The Bard's Tale IV Standard Edition)

This works:
https://www.gog.com/account/gameDetails/1178190421.json

But this does not:
https://api.gog.com/products/1178190421?expand=downloads,expanded_dlcs,description,changelog

(It 404s)

I'm currently building a list using the embed.gog.com address , and I'll run through and try all the game IDs as product IDs for my next trick to see if there's other instances of this happening.

If I understand you correctly you're referring to the games that have a different ID in the catalogue (as in the public sale pages) and the library (your personal bought games). Unfortunately there isn't really a way to connect these two IDs (at least in the useful way that would be of any use) that I've found.

Yeah, my goal was to use the extra information avaialble on the product listing (like whether an extra is a patch or language pack, etc to provide better filtering and tp possibly to use the Galaxy API for downloads) but if there's no useful way of getting that information I'm at a bit of an impasse. Unless anyone is aware of a better way of doing those things.

I've tried to find a way to make it work because my script's changelog links rely on these IDs but the changelogs only load for the product library IDs. But unless the new game cards have changed things there isn't any connection between the two...

Yeah, I was hoping for at least a programmatic method (eg using one of the links from the account to stepover) if not a numeric conversion.

I guess it might be possible to use product names but I dount that will help with unlisted items in any case so it's unlikely to be worth the trouble.

It's so weird that GOG keeps information about which files associated with a game are patch files / lanaguage packs /etc and the Galaxy API download links on the product page but not on the account game details page.

There must be some kind of link (the server had to know which games to add to your library somehow) but it's obviously not publicly accessible.

Some games (like those that come in packs) don't even share a name so it's not a perfect solution by any means.

Yeah, it's very frustrating when the information you want is their just not in a way you can use it...

I just posted instructions about how to make your own Galaxy SDK here: https://www.gog.com/forum/general/how_to_make_your_own_galaxy_sdk