Here is the full list of all 31 STAY achievements.
End Quinn's journey with a feeling of Depression
End Quinn's journey with a feeling of Anger
Discover all possible items
End Quinn's journey with a feeling of Bargaining
Unveil all secret rooms
Back to square one
Reach the final chapter with the highest emotional bonding
End Quinn's journey with a feeling of Acceptance and Hope
Become the perfect soulmate and never leave Quinn
Who are you, stranger?
End Quinn's journey with a feeling of Isolation
Dance with the ugliest partner
Cracking the final code
Memories shaped into bits and pieces
Play it cool
Bad hair day not allowed
Don't lose sight of the north
Never leave the magic circle
Hail to the chief
Board game solitaire
A life within a life within a life within...
Guardians, feathers and the unknown
A never-ending book which is not for Bastian
Don't leave during a time interval
Never kill the cat
And then there was light...
Stare at the full moonlight with Quinn
Reach the final chapter with the highest level of trust
End Quinn's journey with a feeling of Denial
Reveal all possible endings
Collect all the other achievements