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