Here is the full list of all 12 Block Smash achievements.
Complete World 1
Complete World 2
Complete World 3
Complete World 4
Complete World 5
Complete World 6
Complete all bonus rounds in World 1
Complete all bonus rounds in World 2
Complete all bonus rounds in World 3
Complete all bonus rounds in World 4
Complete all bonus rounds in World 5
Complete all bonus rounds in World 6