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