Here is the full list of all 22 Monster Blast achievements.
eat 20 fruits
reach experience level 10
reach experience level 20
get 10 kills with the support tower
finish Bob The Blob
finish the Shield Master
finish the Explorer
finish Puffy
finish Slimy Wall
finish Roller Star
finish Jerry Jumper
finish Panzer Boy
finish Mister Tentacle
finish The Nest
finish Rotary King
finish World 1
finish World 2
finish World 3
Mission Completed
kill 1000 enemies
kill 2000 enemies
kill 4000 enemies