Here is the full list of all 38 Iron Crypticle achievements.
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
Complete The Graveyard
Complete The Catacombs
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
Finish A Regular Room Without Using A Weapon Pickup
Get Rainbow Power
Collect All BONUS Letters
Collect 1000 points worth of coins
Finish A Non-Boss, Non-Empty Room Without Taking Damage
Get The Golden Poop
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
Find A Map
Destroy A Fire Bug
Collect 30 Lemons In A Single Game
Complete 10 Waves In Endless Mode