Here is the full list of all 13 Skyling: Garden Defense achievements worth 1,000 gamerscore.
Completed 25 levels
25 cats on head at exit
Reached 50 Exits
Killed 50 Monsters
Completed 20 Levels
Completed 15 gardens
You learned the story of the Skyling gardens!
10 Levels Completed!
Killed 4 Monsters at once
Killed 3 monsters at once
Completed 5 levels
All levels are now unlocked!
Complete 30 levels to unlock