From what I can see, the game received its most recent Steam patch on 12 August 2021. On GOG, there's an update on 20 August 2021, so it stands to reason that the game would be up-to-date here. That being said, the devs are known to have released GOG builds much more infrequently compared to Steam builds during Early Access and the fact that they use different build numbers on GOG and Steam makes it pretty hard to be certain about the current build without actually owning it on GOG.

You might want to also post your question in the Chernobylite sub-forum, since people there probably own the game on GOG and can check whether functions mentioned in the latest patch notes on Steam are available in the current GOG build.

Compare https://steamdb.info/app/1016800/patchnotes/ and https://www.gogdb.org/product/1472128402#builds . Also, regarding the cosmetic White Rose DLC, there was some chatter about the DLC coming to GOG or even some people getting it for free, but I have no idea if that ever worked out.

Yep. It's up to date.

its good in some cases, Activisions 2 good call of duty games reluctantly give Miniscule discounts on 10 year old games, so sometimes forcing big or stingy publishers is a good thing, considering contempt is the industry standard these days

I don't expect any publisher or developer to discount their games. That's their prerogative - the same with additional content or extras. Both go a long way to building goodwill but I wouldn't be outraged if, for example, Bethesda never delivers the Quake Remaster here.

But at a bare minimum I expect games to be functional and if there are bugs, that they should be fixed, and especially if such bugs have been fixed on other platforms.

Hitman (2016) GOTY does not have MacOS nor Linux support on GOG but does so on Steam. Since said support is delivered by Feral we will probably never see that here on GOG.

I stuck to the thread's topic.

That was not meant as criticism of your contribution, in case that's what you mean - pointing out that there is no MacOS or Linux support is a valuable addition to the thread.

I just made a snide remark at Hitman's expense. Unapologetically off-topic, of course ;)

It seems as if Wuppo - Definitive Edition unfortunately has to be added. Wuppo received German localisation on Steam on 09/11/2021.

https://store.steampowered.com/news/app/400630/view/2985312717412948005

Does not seem to have arrived here on GOG yet. Will contact them and ask about it.

Wuppo on GOG does have German localization, I've just tried it for myself. I think this got added in version 1.37, which was released on GOG on 2021.09.10 according to

https://www.gogdb.org/product/1173909540#changelog

I've never received an update notification for that though and the store page wasn't updated either it seems.

The following languages are available in Wuppo on GOG:

English, Korean, Chinese, Brazilian Portuguese, Polish and German

Thank you. I have to confess that I did not test it myself but I am glad to hear that I was wrong.

Both SUPERHOT games are outdated, again.

https://www.gogdb.org/product/1456141688#builds
https://steamdb.info/app/322500/patchnotes/

https://www.gogdb.org/product/1823091894#builds
https://steamdb.info/app/690040/patchnotes/

Kingdom Rush Frontiers seems to be missing the following update on GOG:

https://store.steampowered.com/news/app/458710/view/2938023743430840925

I just asked in their official Discord about the updates. Now we wait for their reply.

I've been on the Wuppo devs everytime it gets a new update on Steam. :D