Here is the full list of all 27 Squarism achievements.
Spend 20 minutes solving single level
Destroy your only movable shape
Spend 5 wonderful minutes in credits menu
Solve last level
Solve everything
Finish 60 levels
Sacrificed
Finish 50 levels
Opened
Finish 40 levels
Guided
Hivemind
Finish 30 levels
Spend 3 minutes in level selection menu
Breached
Finish 20 levels
Use restart 10 times
Sticked
Spend 5 minutes solving single level
Complete level with that huge 4x4 square
Finish 10 levels
Fail level 3 times
Make wrong shape
Complete tutorial levels
Complete level after 5 restarts
Use restart
Complete first level