Here is the full list of all 21 The Shattering achievements.
Act 1 Completed
Cracked the safe code
Collected all 9 drawings
Found the torn photo piece
Discovered the balloon's secret
Grabbed every toothbrush
Act 2 Completed
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
Liar liar pants on fire
Found the scissors
Approached all the children at playtime
Smartest kid in the class
Made it to the interview on the first try
Keep the cold out