Here is the full list of all 32 Hell Pie achievements.
Get all outfits
Use private insurance
Collect everything
Collect all Candymeat
Collect all Lucky Cats
Collect all Unilambs
Hit 10 humans in the factory
Destroy the crosses in Heaven
Defeat the Hell Pie
Complete the Wing Horns Challenge Level
Unlock Nugget Fart
Witness a dark ritual
Plug in all Wi-Fi sticks
Bring all sexy plants together
Complete the Arm Horns challenge level
Complete the Light Horns challenge level
Defeat Gluttony
Collect 10000 crystals
Monty Python did it with style, don't know how it's done here
Complete dining room side quest
Buy your first outfit
Trigger whale explosion
Collect 5000 crystals
Complete the Ram Horns challenge level
All Munchers freed
Defeat the boss of the Sewers
Collect 1000 crystals
Complete the Sprint Horns challenge level
Collect your first ingredient
Smash Nugget against the wall
Meet Cupid
Meet Chef