Here is the full list of all 15 Mystery of Neuschwanstein achievements.
Analyze rock samples and Ludwig's letter.
Complete chapter VI.
Find all of Ludwig's diary pages.
Discover a tomb.
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.
Solve all the hacking mini games.
Solve all lockpicking mini games.
Repair the shredder and the dynamo.