Here is the full list of all 23 Mallow Drops achievements.
Sent a block out of bounds
Completed World 1
Completed World 2
Completed World 3
Completed World 4
Completed World 5
Found the hidden item in World 1
Found the hidden item in World 2
Found the hidden item in World 3
Found the hidden item in World 4
Found the hidden item in World 5
Enter Sequence 1
Enter Sequence 2
Enter Sequence 3
Enter Sequence 4
Enter Sequence 5
Rotated 50 Times
Died 20 Times
Finished a Puzzle without dying
Finished a puzzle without rotating
Sent all blocks in a puzzle out of bounds
Killed an enemy with a laser
Sent an enemy out of bounds