Here is the full list of all 16 The Sojourn achievements.
Finish your sojourn
Earn all merits of life
Earn 40 merits of life
Witness the story of the first movements
Witness the secret behind the tree
Earn 30 merits of life
Open the frozen well
Reach the top of the tower
Earn 20 merits of life
Earn 10 merits of life
Activate the elevator
Earn your first merit of life
Experience the first chapter of life: Discovery
Witness the story behind the blindfold
Overcome the second challenge
Step into the dark world