Here is the full list of all 27 Pixel Puzzles 2: Halloween achievements.
Complete All Puzzle
Complete Puzzle 25
Complete Puzzle 20
Complete Puzzle 22
Complete Puzzle 23
Complete Puzzle 13
Complete Puzzle 15
Complete Puzzle 17
Complete Puzzle 14
Complete Puzzle 7
Complete Puzzle 9
Complete Puzzle 16
Complete Puzzle 21
Complete Puzzle 6
Complete Puzzle 5
Complete Puzzle 3
Complete Puzzle 12
Complete Puzzle 19
Complete Puzzle 18
Complete Puzzle 24
Complete Puzzle 4
Complete Puzzle 8
Complete Puzzle 11
Complete Puzzle 2
Complete Puzzle 1
Pumpkin Puzzle Complete
Complete Puzzle 10