Here is the full list of all 21 The Shattering achievements.
Act 2 Completed
Grabbed every toothbrush
Smartest kid in the class
Discovered the balloon's secret
Collected all 9 drawings
Act 1 Completed
Cracked the safe code
Liar liar pants on fire
Found the torn photo piece
Broke in and found the files
Ate the pizza
Act 4 Completed
Put together the statue
Back to reality
The loop continues
Game Completed
Act 3 Completed
Found the scissors
Approached all the children at playtime
Made it to the interview on the first try
Keep the cold out