I just need to add a game to my games Library.
I use Linux, & you have something associated with that game that helps it run smoothly on Linux.

I'm not really interested in your site beyond that, not actually.

Figure out how to describe how to download Gog Galaxy.

I think that the Games Library should not require a download nor purchase, not at all.

Friendly ease of use would help your site.
You're already getting activity, & you're advertising a lot about games that you have for sale.
Obfuscating that experience with any sort of insistences that lean towards purchase actually is a terrible marketting strategy, imo.

You sound like a troll. Gog is a commercial enterprise, why should they help you, when you explicitly write that you don't intend to buy anything from them. Bizarre complaint.

https://www.gog.com/game/beneath_a_steel_sky

Here you go, the case is solved.

Exiting the bed from the other side may have been a better idea ?.

I see you are looking for a game launcher on Linux. Bad news: You won't find an official GOG Galaxy download for Linux as there is none.

But, as a handy tutorial I found a couple of weeks back explained, there are ways around that issue.

Obviously, you could still attempt to run GOG Galaxy via WINE. However, this is won't help you much as the tutorial claimed, the Galaxy client on WINE still attempted to install Windows versions when hitting the install button, ignoring the fact that it ran on a Linux system.

The tutorial recommended instead to use Lutris, connect Lutris to your GOG account, and import your GOG games to the Lutris library, then download and install your games through Lutris directly, rather than using the GOG website and install scripts. They claimed that this was working well for most (but not all) games, even on other platforms.

Adding a game you don't own on GOG to your library on the GOG website is not officially supported. It was offered for a (very) limited number of titles during the "reclaim your game" and "GOG connect" campaigns, both of which seem to have since been discontinued. However, you can definitely still add any game you own on any platform to GOG's Galaxy launcher as well as Lutris (obviously).

I would recommend you check out the Lutris website. They got wiki pages and information on how to get you up and running.

Hope it helps.