Here is the full list of all 20 Flynn and Freckles achievements.
Find 10 totems.
Defeat the Snake Queen.
Find Freckles' Sword.
Find 1 totem.
Get 1500 coins.
Cut 1000 grass.
Get 500 coins.
Cut 500 grass.
Get 250 coins.
Kill 15 chickens
Summon the Devil Chicken.
Cut 100 grass.
Kill 5 chickens.
Hit the training dummy 20 times.
Get 100 coins.
Kill 1 chicken.
Defeat Captain Kroaq.
Find all totems.
Die in the cauldron of the fish tribe.
Finish the game.