Here is the full list of all 20 Ghost of a Tale achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Complete the game without getting hit by an enemy.
Complete the game without ever eating to regain energy.
Complete the game without alerting any guards.
Reach the end of the game.
Finish every secondary quest.
Complete the full set of Duinlan's armour.
Rid Dwindling Heights of all spiders.
Unlock forty-five footnotes.
Set fire to all inflammable items in Dwindling Heights.
Steal all of the Rat Guards' handkerchiefs.
Learn all skills in the adventure.
Complete all of Gusto and Fatale's quests.
Reach the desolate shore.
Play all songs during the course of the game.
Discover the name of every possible character in Dwindling Heights.
Open all window shutters.
Discover Duinlan’s tomb.
Gather fifty-five mushrooms.
Reach the highest point in the highest tower.
Escape from Tilo’s cell.