Grargar: Interesting... I didn't know that GOG was counting in-game achievements as being part of the "Achievements" feature.
They don't. Among my owned games (I have an
illegal number of them and should probably buy something soon), it's just Maj'Eyal with its DLCs and Democracy: Africa. Democracy: Electioneering (the DLC I don't have) is also a candidate.
edit: meanwhile, it's quite possible there are games which actually have Galaxy achievements but don't have the achievements tag. Quest for Infamy could be one such game... except it only has two Galaxy achievements, both are secret and probably don't work, so I believe the absence of the tag is justified. I'm not going to go game by game though, Galaxy navigation is just soooooooo slooooooooow.