Here is the full list of all 55 Silent Descent achievements.
Survived Section 45
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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
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Survived Section 21
Complete the Picture Light- up Puzzle
Survived Section 20
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Survived Section 15
Survived Section 14
Survived Section 13
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
Find and Read All Notes
Find and Read Half of All Notes
Survived Section 1