The Binding of Isaac has 113 Secrets (As of Eternal Edition v1.666) that can be unlocked. Secrets can add different kinds of things to the game, such as Items, Bosses, Characters, etc. They may have corresponding Achievements.
In-Game Secrets List
Basic Progression Unlocks
"A Radioactive Spider" - Finish The Basement. (Collectible item)
"Spelunker" - Finish The Caves. (Collectible item)
"The Womb" - Finish The Depths. (Opens level/chapter)
"Monstro's Tooth" - Defeat every regular boss from The Basement. (Activated item)
"Lil Chubby" - Defeat every regular boss from The Caves. (Collectible item)
"Loki's Horns" - Defeat every regular boss from The Depths. (Collectible item)
Character and Combo Unlocks
"The Lucky Foot" - Get 55 pennies in a single playthrough. (Collectible item)
"Magdalene" - Get 7 health containers in a single playthrough. (Playable Character)
"The Yum Heart" - Get 7 health containers in a single playthrough. (Activated item)
"Judas" - Defeat the boss in The Womb 2 for the first time. (Playable Character)
"The Book of Belial" - Defeat the boss in The Womb 2 for the first time. (Activated item)
"???" - Defeat the boss in The Womb 2 for the tenth time. (Playable Character)
"A Poop" - Defeat the boss in The Womb 2 for the tenth time. (Activated item)
Game Completion Unlocks
"A Noose" - Defeat the boss in The Womb 2 for the second time. (Collectible item)
"The Nail" - Defeat the boss in The Womb 2 for the third time. (Activated item)
"A Quarter" - Defeat the boss in The Womb 2 for the fourth time. (Collectible item)
"A Fetus In A Jar" - Defeat the boss in The Womb 2 for the fifth time. (Collectible item)
"Everything is Terrible!!!" - Defeat the boss in The Womb 2 for the sixth time. (Difficulty Increase)
"The Wafer" - Defeat the boss in The Womb 2 for the seventh time. (Collectible item)
"Money = Power" - Defeat the boss in The Womb 2 for the eighth time. (Collectible item)
"It Lives!" - Defeat the boss in The Womb 2 for the ninth time. (New Boss)
"A Bag of Pennies" - Defeat the boss in The Womb 2 with Cain. (Collectible item)
"A Robo-Baby!" - Defeat the boss in The Womb 2 with Judas. (Collectible item)
Special Bosses and Loot
"Something from the Future!" - Finish the Basement 25 times. (New Boss)
"Little Steve" - Defeat Steven (alternate boss). (Collectible item)
"Something Cute" - Finish the Caves 20 times. (New Boss)
"Little C.H.A.D." - Defeat C.H.A.D. (alternate boss). (Collectible item)
"Something Sticky" - Finish the Depths 30 times. (New Boss)
"Little Gish" - Defeat Gish (alternate boss). (Collectible item)
"The Harbingers" - Defeat the Boss in The Depths 2. (New Bosses)
"The Book of Revelations" - Defeat any Harbinger/Horseman. (Activated item)
"A Cube of Meat" - Defeat the Boss in The Depths 2. (Collectible item)
"The Book of Sins" - Defeat all of the Seven Deadly Sins over multiple playthroughs. (Activated item)
Separate Task Based
"A Small Rock" - Destroy 50 tinted rocks over multiple playthroughs. (Collectible item)
"Mr. Mega!" - Destroy 10 tinted rocks over multiple playthroughs. (Collectible item)
"A Halo" - Defeat the Boss in The depths 2 (Mom) by using the Bible. (Collectible item)
"Mom's Contact" - Collect Mom’s eye and another Mom item in the same playthrough. (Collectible item)
"Mom's Pill Bottle" - Use several Blood Donation Machines in multiple playthroughs. (Activated item)
"The Common Cold" - Collect any two of the following: Roid Rage, The Virus, and Growth Hormones, in the same playthrough. (Collectible item)
"A Bandage" - Make a Meat Boy (obtain 4 Cubes of Meat in the same playthrough) (Collectible item)
"The Necronomicon" - Use the Death Card 4 times over multiple playthroughs. (Activated item)
"The Parasite" - Collect two "dead things" (Bob's Rotten Head, Dead Cat, Max's Head, Tammy's Head) in a single playthrough. (Collectible item)
"The Pinking Shears" - Die 100 times. (Activated item)
"A Lump of Coal!?" - Defeat Krampus. (Collectible item)
No Damage Achievements
"Basement Boy" - Finish the two Basement/Cellar levels without taking any damage. (You just need to kill the bosses, you don't have to clear all of the rooms).
"Spelunker Boy" - Finish the two Caves/Catacombs levels without taking any damage. (You just need to kill the bosses, you don't have to clear all of the rooms).
"Dark Boy" - Finish the two Depths/Necropolis levels without taking any damage. (You just need to kill the bosses, you don't have to clear all of the rooms).
Halloween Update
(Some of these may be wrong)
"The Razor" - Finish The Womb with Eve. (Activated item)
"Mom's Knife" - Kill Satan with Isaac. (Collectible Item)
"Eve" - Make 2 Separate Devil Room Deals in one playthrough. (Playable Character)
"A Curse" - Make 2 Separate Devil Room Deals in one playthrough. (Collectible Item)
"The Monster Manuel" - Kill Satan with Judas. (Activated Item)
"A Dead Bird" - Make 2 Separate Devil Room Deals in one playthrough. (Collectible Item)
"A Bag of Bombs" - Kill Satan with Cain. (Collectible Item)
"Guardian Angel" - Kill Satan with Maggy. (Collectible Item)
"A Demon Baby!" - Kill Satan with Eve. (Collectible Item)
"A Forget Me Now" - Kill Satan with ???. (Activated/Consumable Item) [Takes up your item slot and dissapears when used]
"Golden God!" - Unlock all secrets and complete the Collection.This achievement can be gained by collecting all but one of the items if you have defeated Krampus and found the lump of coal.
Title screen with Golden God achievement unlocked.
Wrath of the Lamb In-Game Secrets List
Characters
"Samson" - Complete Depths 2, but pass on 2 Treasure Rooms. (Playable Character)
Game Completion Unlocks
"The D20!" - Complete the Cathedral as Isaac. (Activated Item)
"The Crucifix" - Complete the Cathedral as Maggy. (Collectible Item)
"Abel" - Complete the Cathedral as Cain. (Collectible Item)
"Curved Horn" - Complete the Cathedral as Judas. (Trinket)
"Sacrificial Knife" - Complete the Cathedral as Eve. (Collectible Item)
"Rainbow Baby <3"Complete the Cathedral as ???. (Collectible Item)
"Bloody Lust" - Complete Womb 2 as Samson. (Collectible Item)
"Blood Rights" - Complete Sheol as Samson. (Activated Item)
"Bloody Penny" - Complete the Cathedral as Samson. (Trinket)
"The Polaroid" - Complete the Cathedral six times. (Trinket)
The Chest
"Isaac's Head" - Complete The Chest as Isaac. (Trinket)
"Maggy's Faith" - Complete The Chest as Maggy. (Trinket)
"Cain's Eye" - Complete The Chest as Cain. (Trinket)
"Judas' Tongue" - Complete The Chest as Judas. (Trinket)
"Eve's Bird Foot" - Complete The Chest as Eve. (Trinket) [V 1.48: Unlocked by completing the Chest as ??? instead]
"???'s Soul" - Complete The Chest as ???. (Trinket) [V 1.48: Unlocked by completing the Chest as Eve instead]
"Samson's Lock" - Complete The Chest as Samson. (Trinket)
Challenges
"The Candle" - Complete Challenge 1. (Activated item)
"Lucky Toe!" - Complete Challenge 2. (Trinket)
"Burnt Penny" - Complete Challenge 3. (Trinket)
"Guppy's Tail" - Complete Challenge 4. (Collectible item)
"A Fish Head" - Complete Challenge 5. (Trinket)
"Mega Fetus" - Complete Challenge 6. (Collectible item)
"Super Fan" - Complete Challenge 7. (Collectible Item)
"Spider Butt" - Complete Challenge 8. (Activated item)
"Counterfeit Coin" - Complete Challenge 9. (Trinket)
"The Egg Sack" - Complete Challenge 10 (Collectible item)
Task Based
"Guppy's Hairball" - Transform Isaac into Guppy. (Collectible item)
"Dad's Key" - Complete The Chest with any character. (Activated item)
"!Platinum God!" - Collect 198 items and unlock all other 97 secrets.
"Platinum God!" - Achieve the Platinum God secret. (New Backdrop)
"A Forgotten Horseman" - Destroy a total of 30 Tinted Rocks. (New Boss - Conquest)
"Something Icky!" - Complete the Womb or Utero 15 times. (New boss - Triachnid)
"The Left Hand" - Unlocked by defeating Ultra Pride. (Trinket)
"Stop Playing!" - Kill Mom over 200 times. (New backdrop)
Eternal Edition In-Game Secrets List
The Chest
"You Are Eternal" - Complete The Chest as Isaac in Hard Mode.
"You Are Eternal" - Complete The Chest as Maggy in Hard Mode.
"You Are Eternal" - Complete The Chest as Cain in Hard Mode.
"You Are Eternal" - Complete The Chest as Judas in Hard Mode.
"You Are Eternal" - Complete The Chest as Eve in Hard Mode.
"You Are Eternal" - Complete The Chest as ??? in Hard Mode.
"You Are Eternal" - Complete The Chest as Samson in Hard Mode.
Task Based
"Eternal Mom" - Defeat Mom in Hard Mode.
"Eternal Heart" - Defeat Mom’s Heart/It Lives in Hard Mode.
"Eternal Life!!!" - Gain 7 health upgrades from Eternal Hearts in Hard Mode.
"Eternal Satan" - Defeat Satan in Hard Mode.
"Eternal Isaac" - Defeat Isaac in Hard Mode.
"Eternal Blue..." - Defeat ??? in Hard Mode.
"Eternal Personalities" - Complete The Chest with every character in Hard Mode.
"!!Eternal God!!" - Unlock all other secrets.
"Eternal God!" - Complete the game. (New backdrop)
Bugs
- Secrets might be missing even though they have already been earned, due to various Anti-Virus programs, CCleaner (Or similar cleaner programs) or Steam's Cloud Sync.
- For a detailed description on how to fix the missing secrets, check the video below.
Videos
