After being dormant for a while, GOG Connect is now active again, offering free GOG copies of certain games if you already own them on Steam. It's not currently clear how long these will remain available, so don't delay too long if you're interested!
The currently available games are as follows:
Anno 1404: Gold Edition
The Last Federation
Two Worlds Epic Edition
AI War: Fleet Command
Baldur's Gate: Enhanced Edition
Hot Tin Roof: The Cat that Wore a Fedora
Shadow Warrior (2013)
The Incredible Adventures of Van Helsing: Final Cut
HOW DOES GOG CONNECT WORK?
To connect your library with GOG.com, sign in to your active Steam account via this page. NOTE: Make sure your Steam Privacy Settings & Profile Status are set to public.
You'll be able to permanently import all the games listed below to your GOG.com library – assuming you own them. The eligible games are limited-time offers made possible by participating developers and publishers, so stay tuned for more games to come.
You can connect only one Steam account with your GOG.com library. This process is permanent – choose wisely!