These developers don't seem very interested in GOG users, since:

1. They released the game on GOG more than 2 years late.
2. Despite the abnormal delay they didn't care to implement GOG Galaxy achievements.
3. And they didn't bother to implement online multiplayer.

4. Mac version not on GOG.

lets be quite honest. Not sure many devs bother with achievements on GOG (good number of people dont seem to care either...)
Many games arent released here from day 1. At least my impression is (cynical as it is) the majority of the time devs bring games here later once the income from steam sales dries up. The devs who actually care release stuff here from day 1 to get to as much of the target audience as possible. GOG needs to up their game.. there's plenty of indie games which might be very good which they either seem to dont bother try to get here or the devs say no etc.

What a coinkidink. I emailed the devs about this like 10 months ago and they said it's coming they just needed to work out the multiplayer because GOGs different. Thought 'screw it' and ended up buying on the place you know your game will always be up-to-date literally 2 weeks ago. Oh well, I'm just one person.

What happened to the Linux release? It is available elsewhere. Is this another victim of missing Galaxy support? Doesn't it already list Linux on Steam?

See: https://www.gamingonlinux.com/2020/04/kingdom-two-crowns-grows-bigger-with-a-free-dead-lands-expansion-out-now

You are absolutely right... But I'm afraid they're using Proton. (all Linux sales are Steam keys !)

The articles on gamingonlinux are always very interesting, but I noticed that a Proton version on Steam represents a version of Linux for Liam.
I have often taken for granted, some games which do not have a Native version.
And therefore will never be sold for Linux, other than on Steam and its connection DRM.

I think it's important to show developers who stop by here on GOG, that there's a real interest in releasing a Native version, I invite you to put a small message to them ;-)
It doesn't cost anything, and if you're interested in gambling, it's probably useful.
it is here on GOG that "Kingdom Two Crowns" interests we.