Here is the full list of all 32 Castle achievements.
Acquire all the trophies of the Wall of Fame.
Prevent 200 bomb explosions
Get rid of 200 Burrholes
Put 200 Golden Blues to sleep
Extinguish 200 castle fires
Send 100 Silver Reds to the land of dreams
Fail 10 times
Roast 200 Poulthieves
Fix 100 Clorm damage
Complete the King Mode
Send 25 Silver Reds to the land of dreams
Make 100,000 points in the Protect the Castle mode
Prevent 50 bomb explosions
Get rid of 50 Burrholes
Complete the Protect the Castle mode
Extinguish 50 castle fires
Put 50 Golden Blues to sleep
Roast 50 Poulthieves
Prevent 20 bomb explosions
Get rid of 20 Burrholes
Put 20 Golden Blues to sleep
Complete the Humble Builder mode
Earn a grand total of 50,000$ throughout a game (Money spent in the shop isn't deducted from this)
Complete the game in Normal mode
Extinguish 20 castle fires
Roast 20 Poulthieves
Fix 25 Clorm damage
Send 10 Silver Reds to the land of dreams
Fix 10 Clorm damage
Buy everything from the shop (max. upgrades + max. items)
Complete Level 12 in Normal Mode
Complete Level 6 in Normal Mode