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