Here is the full list of all 29 GYLT achievements.
Escape with Sally
Escape with Emily
Escape from Helplessness
Reach the Final Mine
Defeat Violence
Reach the Basketball Court
Access the Art Building
Defeat Exposure
Get into the Theater
Blind Three Enemies at the Same Time
See the weirdness in the school
Try to Play other of Tequilaworks Game
Remove the battery from the Arcade core
Get outside of the school courtyard
Kill an enemy with a Stealth Attack
Defeat an Enemy with the Flashlight Beam
Enter the school looking for Emily
Use the Planks to Remain Dry
Escape with Both Sally and Emily
Escape from the Arcade without being detected by Exposure
Defeat Violence in the Laboratory Without Being Hit
End the Game without Killing Anyone (without bosses)
Hoop a can
Shock an Enemy
Hit an enemy with a can
Freeze an Enemy and Push Him
Freeze one Enemy of Each Type
Get all the Diaries
Free all the Inhabitants