I’m getting a bit concerned that I can’t find any related announcement on GOG or elsewhere. I got the news and the link from Epic Bundle, which is a site I use mostly to keep track of new bundles. But the fact that the giveaway is not advertised on GOG’s front page nor on their FB page makes me wonder about the source of this redeem link. Hope it’s not anything shady.
Edit: Ignore, it’s legit :-)