Here is the full list of all 19 Curse of the Crescent Isle DX achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
Complete a stage in co-op
Let a Carfee fall in the water
Complete Speed Run Mode
Complete the game with no coins
Collect all 27 coins in the game
Complete the game as the Queen
Hit the third boss three times on its way up
Break one of those big rocks
Take damage by staying underwater too long
Complete the Boss Rush Mode
Complete the game as the King
Defeat Aranomanom
Find one of the special messages in the password screen
Talk to the statue in the town
Defeat Naja Naja
Defeat Grondor of the Forgotten Mine
Jump off an enemy while grabbing him
Complete a stage without taking damage
"Accidentally" kill an enemy