My apologies for reviving this (effectively) dead thread, but I saw little point in making another thread for the exact same reason, given how little activity there is in the forum here.
The 4 Days of Night event will not be coming to GOG this year either, from the indications.
The attached image is a screen capture of part of the email from Hinterland regarding the event, and particularly notable is that the notice indicates the update is coming to Steam; not PC.
This is highly disappointing, though not all that surprising.
I bought The Long Dark here on GOG mainly because I did not have internet access at home at the time.
Despite the internet access I now have at home still being somewhat limited, I now somewhat regret buying The Long Dark here on GOG, as I am excluded from this event, again.
I could understand the reluctance of Hinterland releasing the 4 Days of Night event on a DRM-free platform, where people could just save an installer and play it again at will any time of the year...
Except, I'm left with the fact that it was done once before, and the thought of "Who cares?"
As I understand it, you can do the same thing on Steam by making a backup of the game during the event, and then installing that version and refusing to update it.
To me, it seems as though Hinterland would prefer if the GOG release disappeared, seemingly ignoring this release much of the time, excluding customers here from this event, and only pushing major patches.
Due to this experience, I may refrain from buying any Hinterland products, regardless of the platform or storefront, in the future.