Here is the full list of all 55 Silent Descent achievements.
Survived Section 45
Survived Section 44
Survived Section 43
Survived Section 42
Survived Section 41
Survived Section 40
Survived Section 39
Survived Section 38
Survived Section 37
Survived Section 36
Survived Section 35
Survived Section 34
Survived Section 33
Survived Section 32
Survived Section 31
Survived Section 30
Survived Section 29
Survived Section 28
Survived Section 27
Survived Section 26
Survive a Chase Encounter
Survived Section 25
Solve the Flip Switch Puzzle
Solve the Letter Flip Puzzle
Survived Section 24
Survived Section 23
Find and Read All Notes
Survived Section 22
Survived Section 21
Complete the Picture Light- up Puzzle
Survived Section 20
Survived Section 19
Survived Section 18
Survived Section 17
Survived Section 16
Survived Section 15
Survived Section 14
Survived Section 13
Find and Read Half of All Notes
Survived Section 12
Survived Section 11
Survived Section 10
Find and Collect All Hidden Picture Pieces
Survived Section 9
Survived Section 8
Complete the Letter Light-up Puzzle
Survived Section 7
Acquire a Flashlight
Survived Section 6
Survived Section 5
Survived Section 4
Survived Section 3
Survived Section 2
Survived Section 1