Here is the full list of all 38 Iron Crypticle achievements.
Finish A Regular Room Without Using A Weapon Pickup
Complete The Catacombs
Get The Golden Poop
Complete The Graveyard
Find A Map
Finish A Non-Boss, Non-Empty Room Without Taking Damage
Defeat 3 Types Of Miniboss
Defeat A Boss Without Using A Weapon Pickup
Defeat A Boss Without Taking Any Damage
Pick Up 10 Hearts In A Single-Player Game Session
Complete The First Floor On Hard Difficulty
Defeat Boulderface
Defeat The Giant Peepwort
Defeat Gnasher
Defeat Hexapod
Defeat Madame Tentacles
Defeat The Phantom
Collect Or Buy 5 Stat Increases In A Single Game
Use The Atomic Fist 20 Times
Complete An Infestation Room
Complete The Mud Pits
Defeat 1000 Monsters
Collect 1000 Food Items (Increasing Score Type)
Buy 10 Items In A Shop
Clear 50 Rooms Of Monsters
Complete Castle Crushers 3 times
Get Rainbow Power
Collect All BONUS Letters
Collect 1000 points worth of coins
View 20 Item Descriptions In The Ledger
Defeat A Boss In All Its Incarnations
Get 100 100x8s In A Single Game
Find The Golden Kitty
Use 10 Different Weapon Types
Use 5 Different Scroll Types
Destroy A Fire Bug
Collect 30 Lemons In A Single Game
Complete 10 Waves In Endless Mode