Here is the full list of all 16 Return of the Obra Dinn achievements worth 1,000 gamerscore.
Solve the entire book.
Solve all fates in chapter X.
Solve all fates in chapter IX.
Solve all fates in chapter VII.
Solve any 45 fates.
Solve any 30 fates.
Solve all fates in chapter VI.
Solve all fates in chapter V.
Solve all fates in chapter IV.
Solve any 15 fates.
Solve any 6 fates.
Solve all fates in chapter III.
Solve all fates in chapter I.
Solve all fates in chapter II.
Leave the ship without solving all available chapters.
Loosely true, in the eyes of Company and Crown.