Here is the full list of all 19 Lamentum achievements worth 1,000 gamerscore. It takes around 4-5 hours to unlock all of the achievements on Xbox One.
Unlock the "Sacrifice" ending.
Unlock the "Redemption" ending.
Unlock the "Ritual" ending.
Unlock the "Cowardice" ending.
Find the mysterious lady outside Grau Hill.
Some words are written in blood.
The origami dragonfly.
Help the illusionist escape from Grau Hill.
Find Lily at the Grau Hill exit.
Welcome to Grau Hill.
The nightmare begins.
The strange old man.
Descend through the spirals of madness.
A pathetic violinist.
Love is eternal
Who is on the other side of the mirror?
Will you come back for me?
The end of the nightmare.
Can you decipher a language lost in time?