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