The achievements seems to be broken. When I finish the ritual at the start of the game, the achievement "Magic" is not unlocking. I've tried it at two different PC's.
Any ideas?

I'm having the same problem, though I got "The End?"

I just beat the whole game, and not a single achievement unlocked in Galaxy. Definitely broken. GOG Galaxy doesn't show a single achievement unlock amongst any of the 181 people I have on my GOG friend list in the past two years. It's possible that none of them have played in that long, but my guess is they've been broken for at least two years.

Broken game.
No setting to change monitor or go to windowed mode, can't play it.

Same

Yeah sadly some achievements are still broken. Mostly story-related, for the main game. For me the ones that won't unlock are:

Magic: Perform the Ritual (should be unlocked automatically after finishing the 2nd level
The End?: Finish the Game (create the final potion without using the flower)
True Ending: Break the Mirror (create the final potion and use the flower, if you find all 7 of them)

Soldier: Never Miss Your Target where you aim and shoot the mortar at the 5th level was initially buggy for me, but after my save was mysteriously wiped I was able to get it after replaying the level.