Here is the full list of all 29 Kingdom Defense achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Set fire shells
Level 12 completed
Level 11 completed
Level 10 completed
Level 9 completed
Level 8 completed
Level 7 completed
Level 6 completed
Level 5 completed
Level 3 completed
Level 4 completed
Set trap
Build magician tower
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English language
Disable sounds
Level 2 completed
Improve hp
Improve speed
Exit the game
Level 1 completed
Sell tower
Improve damage
Build knights tower
Use mini knights help
Improve accurancy
Build archers tower
Exit the main menu
Enable sounds