I asked for more information about what's going on with the patch + GOG, unfortunately it doesn't look good:
We had a very tight budget to do this patch, and we really wanted to push as far as possible to serve the community.
Upgrading the engine version to optimize game performance and present a better experience to players created issues with the GOG SDK that we haven't been able to fix properly.
We have proposed to GOG to upload a version without the achievements (which were causing the most troubles), but they did not accept.
We thought we could do it, as we pushed Omensight without achievements for the same problem.
We finally ran out of time and had to move forward on our next project, and we closed the patch production cycle without GOG.
We are really sorry for the disappointment and we'd like to thank you very much for your understanding.
IMO it's silly for GOG to refuse the patch over such a minor feature as achievements :/ Especially considering the kind of improvements and fixes it brings.
I suggested the possibility of making it available under a separate library entry so that users can decide for themselves which to use (as has been done with a number of other games here already where significant changes have been made), but whatever happens will likely be up to GOG. I understand GOG doesn't like the idea of having to drop any features, but missing out on the patch entirely is even worse - and GOG already has a bad reputation when it comes to updates.
On the plus side the Steam version is DRM-free though.
Good info... and yah, I have the game on Steam as well, but really like to keep as many games as I can in Galaxy... reality is, though... there are and always will be some games that I'll have to come to grips with that "it's a Steam game" because of the flakiness of GOG on either issues like this or older games that will never see the patches Steam got... the first two SteamWorld games, etc.
Stories like this, though, always knock my love for GOG down several notches... they're wildly inconsistent with stuff like this (rejecting a game cause of no Achievements), cause look at Parkitect... just launched out of InDev, no Achievements but the Steam version has them... Return of the Obra Dinn, recent launch, no Achievements but the Steam version has them... so explain that one to us, GOG
Good to know it's DRM-free on Steam... I didn't even check myself, yet, to see if it would launch without Steam being open... I always keep any DRM-free games on Steam installed and just copy the game folder to a backup drive and keep a copy that way, updating when any updates hit
Oh... and regarding what the devs said about this... GOG needs to step up their work on Galaxy... really tired of games launching WITH Achievements but with no Overlay support because "the Overlay is not compatible"... ugh... they need to pump up the quality of the SDK and the tech behind the Overlay