You seem to be under the mistaken impression about a couple of things at least.

1. That GOG have much more power than they do.
2. That DRM-Free is accepted much more widely than it is, when really it is just tolerated by some and not at all by others. Only a few actually champion it, and it may well eventually go the way of the Dodo. DRM is increasing all over the world.

GOG relies on support, rather than game providers relying on GOG.

Mostly talking big DEVs and PUBs here, as Indie games or small independents are a different story.

Make it to onerous at GOG and providers will just stick with where they make most of their sales - Steam.

I'd say add to it that indie devs have reasonable delays and that in cases of unexpected trouble allow extra time .. While AAA games or even AA and maybe even A games need to be decently timely updated.. yet a alloted time frame that matchs the size and scope of the funding/work force allowed A.K.A bigger studio's get a smaller allotted time frame smaller ones get a bigger allotted time frame

As far as I know such clause already exists. However it is not much of use if GOG does not enforce it.
Marking such games as "Outdated" would be a fair option imo. Of course nobody would buy it and maybe this would lead devs to update the game after all. However regarding the pricing that's not up to GOG so putting them on sale is no option.
This might be true for big publishers but I have spoken to several indie devs and they really WANT to be on GOG even though they are on Steam. If you ask me, I'd rather have more of those "I want to be on GOG and support it" indies than those "Well ... we could get some money on GOG as well ... we don't need to put much work in it and can abandon it sooner or later" big publishers - but I am sure that I am in the minority here since most GOGers prefer to have the big publishers and the big games here ... even if that means that support might stop whenever they want.

If I had to wager a guess, the Slime Rancher issue is because they are not using depots for their DLC. My understanding of this kind of approach is that everything's already present in the base game (since these DLC don't download any additional data) and they just do an ownership check through the Steam API that will enable the content in question. This obviously doesn't work for GOG games, as they need something that doesn't rely on external API for the offline installers, like a file system or registry check.

Now I'm certainly not a particularly competent Unity developer, but I'm quite sure I could come up with a work-around for such an issue within an hour or two, like conditional compilation or something similar. For this reason I don't really buy this simply being incompetence, the sheer amount that it would require for this to be a problem would make creating a game of this magnitude infeasible. It would be hard to convince me that this isn't simple laziness to support the game on less lucrative store-fronts.

/rant

This sounds bad, and unfortunately it's not the first time I hear something like it. Perhaps another visit to GOG HQ is in order? :P

Thanks! Good news indeed :p

Nice one!

Yes, this is good news indeed. Thanks for responding and listening to the community!

Can GOG please make sure the update is applied to the offline installers, as well as Galaxy?

Thank you, but it's a shame this keeps happening with gog versions of games.

And please make sure the offline installers for this game are updated as well.

Agreed I may want big games but I much rather indie games if they are supported ..Heck if people need big market games you know AAA and AA even sorta A games .. Then it's best to target the ones thats been out for awhile with all work on em done already and the like .. As while yes I would like newer games then that from em older big games I am more then happy with given my backlog of games thanks to sales

Great news, thank you!

Could you also try to contact Aspyr regarding the latest Stubbs the Zombie update? A user was answered the exact same thing, that the GOG version will not be updated. Also, on the game page there are this exact words:
"Achievements to be implemented at a later date."
And even in this case they said they won't be adding them, so I'd say the description is pretty misleading.

Great work, thank you! Please do Robot Gentleman next, then Bitmap Bureau, then B-evil, then Gears for Breakfast, then Microids, Artefacts Studios, then Łukasz Jakowski, then Z4g0 and Ivan Venturi Productions, then Sigma Team, then Badland Games, then AurumDust, then WadjetEye Games, then Elder Games, then Fictiorama Studios, then Daedalic Studios, then Dreadlocks Ltd., then Capcom, then Star Drifters, then Bedtime Digital Games, then HopFrog, then Nightdive Studios, then KK Game Studio, then Awesome Game Studio, then Gambrinous, then Tomorrow Corporation, then Heart Machine, then Idea Factory Inc., then Coldrice Games LLC, then Tangrin Entertainment, then NIGORO, then Vlambeer, then Triple Eh?, then Eggcode, then Rainbow Studios, then Le Cartel Studio, then Ellada Games, then Lightbulb Crew, then Nightschool Studios, then Mindfield Games, then Humogous Entertainment, then Jacob JJanerka, then Quadro Delta, then Disaster Studio, then Running with Scissors, then IV Productions, then Tomasz Wacławek, then Human Head Studios, then iFun4All S.A., then Fool's Theory, then Mandragora, then Firefly Studios, then SNK-Games Ltd., then JoWooD Productions Software, then Aspyr, then Gas Powered Games, then Lazy Bear Games, then Telltale, then inXile Entertainment, then KING Art, then Baroque Decay, then BonusXP, then Tango Gameworks, then Live Motion Games, then Gamious, then Cyan Worlds, then Haemimont Games, then Dim Bulb Games and Serenity Forge, then Cinemaware and then Rain Games.

... I guess what I'm ttrying to say is that we appreciate you contacting Team17 to fix this game, but there's plenty of work still to do. So what will GOG do about those developers?

I.. didn't expect such a quick positive resolution! :O
Good job!

(and yeah, please also check the "2nd class" + "broken achievs" documents for other many cases like this one)

Could you please look into the "Slime Rancher" DLC problem, too?

https://www.gog.com/forum/general/gog_publisher_says_that_there_are_no_plans_to_update_gog_only_steam_and_epic/post32

And PLEASE kick out the developers from "Party Hard" and "Party Hard 2". Both games have DLCs ELSEWHERE and we have only the main game.