Here is the full list of all 15 Memoir En Code: Reissue achievements.
A message for you
Play until the end without skipping a single track (exc. Otoloop)
Key: Øresund
Key: Laurana
Find every decoding key
Read through all the dev commentary parts
Key: Precisione
Key: Oranje
Key: Lei Disse
Key: Silippo
Find 44.4% of the decoding keys
Key: S.S.S.
Key: Otoloop
Nine keys, one message
Key: Pieces