Here is the full list of all 27 Pixel Puzzles 2: Christmas achievements. It takes around 4-5 hours to unlock all of the achievements on Windows.
Complete All Puzzles
Father Christmas Puzzle Complete!
Cat Puzzle Complete!
Nativity Puzzle Complete!
Taken Puzzle Complete!
Gift Puzzle Complete!
Socks Puzzle Complete!
Merry Christmas Puzzle Complete!
Popcorn Puzzle Complete!
Santa Puzzle Complete!
Cake Puzzle Complete!
Teddy Puzzle Complete!
Presents Puzzle Complete!
Snowman Puzzle Complete!
Nut Cracker Puzzle Complete!
Toy Santa Puzzle Complete!
Mince Pies Puzzle Complete!
Bells Puzzle Complete!
Bridge Puzzle Complete!
Apples Puzzle Complete!
Gnome Puzzle Complete!
Bear Puzzle Complete!
Friends Puzzle Complete!
Cookies Puzzle Complete!
Baubles Puzzle Complete!
Dawn Puzzle Complete!
Complete Santa Hat