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.
Level up your Hero to level 21
Level up your Hero to level 16
Buy some equipment for your Hero
Level up your Hero to level 1
Level up your Hero to level 4
Buy 10 belongings for your Hero.
Level up your Hero to level 10
Complete 3 quests
Create all elements in Main Game
Create all magical creatures.
Invent all spells
Complete 1 quest
Create all 3 towns
Open all elemental elements