I would recommend that people go for this achievement first as the 5 puzzles that are solved count towards the achievements for
and
which means that you should only actually need to play the other 15 puzzles.
Also for those like me who may have 'unlocked' all the achievements prior to the game getting enabled for Xbox Live, it is possible to reset the game.
Using Windows Explorer go to c:\[username]\appdata\local\packages\Hamster.......\LocalState\ and delete the SAV.bin file.