Here is the full list of all 14 Doodle Kingdom achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Complete 3 quests
Create all elements in Main Game
Level up your Hero to level 21
Level up your Hero to level 4
Complete 1 quest
Invent all spells
Create all magical creatures.
Level up your Hero to level 16
Buy 10 belongings for your Hero.
Level up your Hero to level 10
Open all elemental elements
Create all 3 towns
Buy some equipment for your Hero
Level up your Hero to level 1