I really enjoy the game and I got it through GOG, but I'm having this issue where one of the achievements doesn't register. The Sacrifice achievement. I've destroyed Jokers in the Joker slot using the missile card, but it still isn't unlocking.
Weird. It works on Steam and it worked when I tested on GOG. We don't have any different code for GOG because GOG uses a wrapper for the Steam achievement code. So this might be some weird GOG issue. Sorry.
Wait, did you fully close and reopen the GOG launcher? I did that and the launcher updated when it loaded and then I got the achievement. Maybe try that if you haven't already.