Here is the full list of all 26 Amnesia: Memories achievements.
Collected every trophy in the game
Listened to every still image voice
Achieved the Mini Game reward
Unlocked Memories of every character
Won against all five people in Rock-Paper-Scissors
Won against three people in Rock-Paper-Scissors
Won against all five people in Air Hockey
Won against three people in Air Hockey
Unlocked Memories of Toma
Unlocked Memories of Ukyo
Unlocked Memories of Shin
Unlocked Memories of Ikki
Witnessed all of the extra stories
Experienced bad endings in all of the routes
Experienced every possible ending
Experienced normal endings in all of the routes
Experienced good endings in all of the routes
Reached the Good Ending in the Joker World
Reached the Good Ending in the Heart World
Reached the Good Ending in the Spade World
Unlocked Memories of Kent
Reached the Good Ending in the Clover World
Reached a normal ending in one of the routes
Reached a bad ending in one of the routes.
Reached the Good Ending in the Diamond World
Cleared the Prologue