Originally Posted by Inazuma
"Players who didn't use their Steam key can already play via GOG."
How exactly though? What's the magic formula here that I'm missing???

He meant Kickstarter backers, specifically. Kickstarter backers that chose GOG for their digital distribution and never played the alpha/beta release, have been able to download and play the GOG version.

DOS2 Mods: Happily Emmie After and The Noisy Crypt

Steam Workshop
Nexus Mods