Here is the full list of all 15 Mystery of Neuschwanstein achievements.
Complete chapter V.
Complete chapter IV.
Listen to Ludwig's Parrot.
Complete chapter III.
Take a finger print.
Complete chapter II.
Complete chapter I.
Find any of Ludwig's diary pages.
Complete chapter VI.
Analyze rock samples and Ludwig's letter.
Solve all the hacking mini games.
Find all of Ludwig's diary pages.
Discover a tomb.
Solve all lockpicking mini games.
Repair the shredder and the dynamo.