I read that STALKER CD keys that you get when you buy a game from the series on steam can be redeemed on GOG. Is this true? I tried reclaiming and it didn't work but is there something I can do to make it work? Or do I need to connect via GOG connect?

Only retail keys are supposed to be redeemable on GOG. Although some Steam keys may work if you're lucky - my Clear Sky key did.

I see, thanks! I'll have to wait for GOG Connect then.

GOG Connect is almost dead...Not a lot of games get added so I can say for 99% sure the stalker games wont be added.

They were there once before I think, who knows if they might do it again? Hopefully they remember the series during a sale or promo of the next stalker game and bring them back.