Here is the full list of all 42 How To Make A Killing achievements.
Get the Shovel.
Get the Falchion Sword.
Open all chests.
Buy food from a stall.
Get the Odd Rock.
Max out your luck.
Get all possible Empty Potions.
Get the Fireman Hat.
Get the Running Shoes.
Get the Candle.
Get the Ordination Certificate.
Get the Spellbook.
Beat the game without killing a rabbit.
Get all Permanent Hearts.
Find the hidden treasure.
Defeat the Necromancer.
Defeat a Good Bunny.
Defeat a Necroskeleton.
Defeat a Person.
Defeat a Red Devil.
Defeat the Slime King.
Defeat a Trap Chest.
Defeat the Turtle.
Get the Parchment.
Pick a lock.
Get the Magical Ring.
Feed Mark a worm.
Get the maximum amount of coins.
Get a Permanent Heart.
Exchange plants for potions.
Take responsibility for your actions in The Blame quest.
Buy a Throwing Knife from a Stall.
Lead Zcazca to her home.
Give Keith what he wants until he doesn't want it anymore.
Tell Duncan that the Crispiness is Awesome.
Tell Duncan that the Crispiness is Evil.
Sneak attack with Sword.
Sneak attack with the Lightning Spellbook.
Get Tree Fiddy.
Dig up a body.
Blame someone for your own crime.
Complete every quest. Hint: There are 14 total including The Killing.