Welcome to the hospital.
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Hazing - Night Shift
Read the note on the desk in the office.

The doctor's notes.
Not 100% sure how to get that one. Either you have to read all notes at the wall in the office...
Or you have to read all notes in the office that include a clue for the piano puzzle. (The other notes with the clues are at the piano, in the shelf and at the desk.)

The key is through music.
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The solution of the piano puzzle is:
1: upside down interrogation mark
2: V
3: 2 snakes
4: the symbol containing a cicle, a triangle and a line.

Following the White Rabbit.
After the piano puzzle, read the note at the end on the left.

Boo! Got scared!?
Before the second gate, try to open that door on the right.

Pieces of me
Before going through the third gate, take the last door on the right and read the book on the bed.

A great match.
Same room as the previous, solve the chess "puzzle". This one might be story-related.

The secret of King Solomon.
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The Code is : 9531

Good Ending.
Continue on and don't fall through the hole, you have to click at the right moment in the QTE.

Now load (chapter select) chapter 3.

Fell.
Fall through the hole by failing the QTE.

Algernon's Friend.
Approach the toilet in the open cell.

You're crazy.
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You need to run.
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What do you want here?
After interacting with the TV and the lamp after the running section, don't go forward, instead turn around and go back the way we came.

Answered everything correctly.
It's clear what to do.

Here are all the correct answers written down:
Mirror - Distorting
Flower - Wilting
Laughter - Chilling
Whisper - Inaudible
Dream - Unattainable
Star - Twinkling
Wind - The Bearer
Tear - Bitter
Elusive
Darkness - Consuming

After you got the previous achievement, load back chapter 6.

Answered everything wrong.
This time pick the other answer every time.

Fresh air.
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A true connoisseur of art.
Find this statue in the right path of the cemetery in the corner and stare at it a few seconds.

Bad Ending.
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Welcome Back.
You have to load chapter 1 through chapter select.