It says The Witcher (The first one), but I think it might have been a bonus with my purchase of The Witcher 2, since I bought and played the former on Steam first.
I have not bought anything through the GOG platform as I do not have the money to do so, but there are several games that I eventually wish to get from them.
My very first purchase was Duke Nukem 3D Atomic Edition. I got a bunch of freebies though originally: Lure of the Temptress, Beneath a Steel Sky, Teenagent, and Tyrian 2000.