Here is the full list of all 31 Iron Fisticle achievements.
Collect all hint books
Collect 100 treasures
Get the golden bananas
Collect 10 golden goblets
Complete the game
Get garlic breath
Collect a giant piece of cake
Reach max level
Collect 1000 coins
Collect all rainbow gems
Make lemonade
Complete the third floor
Complete a room when entering with only 1 health
Kill 10 enemies using dash
Collect 100 items in the ledger
Complete The Graveyard
Complete the second floor
Collect 5 diamonds
Collect all letters spelling B-O-N-U-S
Get the golden turd
Complete the first floor
Kill a golem
Open 100 chests (any type)
Level up ten times
Buy a gold item in the shop
Kill 1000 Frankies
Complete the bonus game
Complete The Catacombs
Complete the first room
Complete a room without losing any health
Level up once