Rooms

Each floor of the game is made up of a number of Rooms. The number of Rooms on each floor generally increases as the game progresses.

Normal Rooms
Normal Rooms make up the majority of the Rooms on a floor. These Rooms typically contain enemies and may drop a pickup or chest after all enemies are killed. Many Rooms also contain various pickups, chests, items, and obstacles.

Isaac cannot leave a Room with enemies until they are all killed or until a door is opened with an explosion. If Isaac is currently holding an active item, completing a Room with enemies will add one charge.

Rooms can come in various sizes; while normal-sized Rooms are the most common, double and quadruple-sized Rooms can also appear.

L-shaped triple-sized Rooms, narrow hallways, and tiny Rooms can also appear. Additionally, completing a quadruple-sized Room or an L-shaped Room will add two charges to Isaac's active item.
 * The last wave of Boss Rush adds only one charge.

Boss Rooms


Boss Rooms contain one of the many Bosses, with victory granting Isaac an item from the Boss pool, hearts (depending on difficulty), and a trap door leading to the next level.

Mini-Boss Room
Mini-Boss Rooms are identical in appearance to normal Rooms and contain one of the Seven Deadly Sins.


 * Mini-Boss Rooms are iron barred shut upon entering unable to be escaped and opened, even by explosions, until the Mini-Boss is defeated
 * Mini-Boss Rooms have a map icon but don't have a special door.

Normal/Golden Treasure Rooms
A Treasure Room, or Item Room, is guaranteed to appear on all floors From 1 to  2. From Basement 2 and on, this Room requires a key to enter. The Room contains one item from the Treasure Room item pool. Various obstacles may be present, and occasionally Flies or  Greed Gapers/Bulbs will be present. This Room has a small chance to contain two items from the treasure pool that can both be collected, and a very small chance of containing no item pedestal at all, instead containing one poop pile, 3 attack flies, and various pickups, including one trinket.

Golden Treasure Rooms always require one key to open in Greed Mode.


 * Golden Treasure Rooms appear in Greedier mode as well, acting the same way and requiring a key to open.

Golden Treasure Rooms can generate in the / if the Bloody Crown trinket is equipped when the floor is generated.

Golden Treasure Rooms can generate in with the Wicked Crown trinket equipped, and can generate in the  with the Holy Crown trinket equipped.

Silver Treasure Rooms


Silver Treasure Rooms are Rooms found in Greed Mode. They always contain one item from the Greed "Boss" Item Pool, and require no keys to open, being open from the start of the floor.

Appears in Greedier Mode as well, acting exactly the same way

Red Treasure Rooms
When carrying the Devil's Crown trinket, any newly found Treasure Room becomes a Red Treasure Room, which contain items from the Devil Room pool for the price of heart containers. The prices are those normally required in Devil Deals.

Planetariums
Planetariums are similar to Treasure Rooms, but only contain one powerful celestial item belonging to the Planetarium (Item Pool), items exclusive to Planetarium Rooms. Planetariums have an additive and higher chance of spawning if the player avoids walking into Treasure Rooms.

Shops


Shops sell various items in exchange for coins. Shops start at level 0 and only sell 2 items, but Shops at higher levels sell more items. They can be upgraded through the Donation Machine, which can be commonly found in the Shops and sometimes in an Arcade. Shops also have a chance of being replaced by a miniboss Room containing Greed or Super Greed.

Shops can generate in the / if the Silver Dollar trinket is equipped when the floor is generated.

Shops can generate in with the Wicked Crown trinket equipped, and can generate in the  with the Holy Crown trinket equipped.

Has a new Door, no longer sharing a Door with Libraries.

Arcades


These Rooms are locked and require one coin to be opened. Arcades can only spawn on even floors (Basement II, Caves II, Depths II, Womb II, etc) or XL floors if the previous floor was completed with 5 or more coins. Arcades can contain machines, beggars, and other objects.

Due to how alternate chapters work, Arcades will spawn on the first floor of these chapters (Downpour I, Mines I, Mausoleum I, Corpse I).

Normal Challenge Room


Challenge Rooms can only be entered if Isaac's total health (red, black, and soul hearts) is equal to or greater than his number of heart containers. Upon picking up its contents, Isaac has to fight three waves of enemies.

Boss Challenge Room


Boss Challenge Rooms will only generate if Isaac has full health upon entering the floor. They also can only be entered if Isaac has one or less red heart. Its contents are similar to the Normal Challenge Room, but upon picking up its contents, Isaac has to fight two waves of Bosses instead of normal monsters.

Boss Challenge Rooms now can only be entered normally if Isaac's total health (red, black, and soul hearts) is equal to or less than 1 full heart, but now always contain an item from the Boss Item Pool.

Curse Rooms


Curse Rooms feature spikes on the door that hurt Isaac when entering and exiting the Room. Curse Rooms can contain various things, ranging from enemies to items.

Sacrifice Rooms


Sacrifice Rooms are special rooms that have a chance to spawn a chest after Isaac damages himself on the spikes featured at the center of the Room. Sacrifice Rooms have a higher chance to spawn if Isaac has more health to sacrifice.

Sacrifice Rooms now can pay with a much wider variety of rewards.

Has a new bloody door, replacing its old, generic one.

Secret Rooms


Secret Rooms must be bombed into, and are usually surrounded by 3 or 4 Rooms. Secret Rooms usually contain shopkeepers and various pickups.

Super Secret Rooms


Super Secret Rooms must be bombed into, and are only located next to one other non-special Room. They tend to spawn closer to the Boss Room. Super Secret Rooms can contain a variety of pickups.

Ultra Secret Rooms


Ultra Secret Rooms are very secret rooms, found when venturing one Red Room outside the normal map using the , Crystal Key,, or the , or by teleporting to it with. These map-expanding items allow you to create Red Rooms, and if correctly found, one of those new Red Rooms will have a Secret Room passageway to the Ultra Secret Room already opened. The Ultra Secret Room itself contains keys, key blocks, and/or shopkeepers, and one item from the Angel Room item pool for its pedestal rewards.

Libraries


Libraries require a key to be entered and can contain books, cards, runes, and trinkets.

Has a new Door, no longer sharing a door with Shops.

Devil Rooms


These Rooms allow the player to make deals with the Devil by trading health for items. Devil Rooms can also contain red chests, black hearts, spikes, or monsters along with its signature devil statue.

Devil Rooms have a chance to be only a Krampus mini-boss fight, if Krampus is unlocked.

Angel Rooms


Angel Rooms contain an angel statue and an item, soul hearts, or eternal hearts. The Angel Room has a chance to replace the Devil Room if certain conditions are met.

Can now have a confessional in them.

Vaults


Vaults require two keys to open and can contain various things, ranging from items to donation machines.


 * Has a new Door, no longer sharing a Door with Dice Rooms.

Dice Rooms


Dice Rooms require two keys to open. Depending on the number of pips imprinted on the face of the large red die embedded in the floor, stepping onto the center of the die activates an effect.


 * Dice Rooms, when spawning, replace a sacrifice room that also could have spawned on the floor. They have a higher chance of spawning over a sacrifice room spawn if you have 2 keys.
 * Dice Rooms now have a small image in the corner of the large red die that also tells the effect of stepping on it.
 * Has a new Door, no longer sharing a Door with Vaults.

Bedrooms


Bedrooms require two bombs to open. Bedrooms contain a bed that can be used once to restore all of the player's health, or if they have no red hearts, they give you 3 soul hearts and add one charge to their active item.

Depending on if the Bedroom is Clean or Dirty (the main difference being the state of the bed and wall color), bombing the center of the carpet will reveal a crawl space (Clean) or a trapdoor (Dirty) leading to the next floor.

Crawl Spaces


These Rooms are entered through Trapdoors with ladders in them. They can rarely be found under destroyed rocks. They can also be found using, , or under a Clean Bedroom's rug. These Rooms are viewed from the side, rather than the top like the rest of the Rooms in the game. Crawl Spaces usually contain an item or various pickups. Rarely, the Crawl Space will lead to a Black Market.

Black Markets
Black markets are accessed through Rare Crawl Spaces. These Rooms are 2 Rooms wide and have 5 shop items that can all be bought for 1 heart container, like devil deals. Black Markets also have a trapdoor to the next floor and various machines or beggars.

Angel Room Shops
Angel Room Shops are special holy shops, accessed if Isaac has. The Stairway will spawn a ladder in the starting room of each floor that leads to each floor's Angel Room shop, a Shop that sells Angel deal items, has angel-related pickups, sometimes includes a coin beggar or a Confessional, and always includes an angel statue.

Secret Shops


Secret shops are accessed by buying a, opening up a 'special' Shop Trapdoor that leads to the floor's underground shop. Secret shops have a wider variety of items and pickups, sold at various expensive prices.

Red Rooms
Red Rooms are special rooms created when using the , Crystal Key,, or the . The Red Key Rooms don't open without these items, and are spawned into existence at the closest red outline door when the item is used. The new Red Room can be a normal Room on this floor, or any special Room, aside from extra Ultra Secret Rooms and Boss Rooms. Red Rooms can't spawn where there aren't 4 connections out of the Room, not spawning if a touching room contains a bottomless pit on one wall, already is a secret room, or is a thin closet/hallway room. While inside a Red Room, the music of the floor will be slightly distorted.

Red rooms can only be spawned in an 13x13 radius from the the center room of the map, or six rooms from the center room in any direction; any farther will lead to entering an I AM ERROR Room.

I AM ERROR Rooms
I AM ERROR Rooms have a small chance of being reached upon teleporting. Every I AM ERROR Room contains a trapdoor to the next floor along with various pickups or items. The only way out of an I AM ERROR Room is through this trapdoor or by teleporting out.

Using when all other rooms have been explored guarantees to be teleported in an I AM ERROR room. Finding a way to infinitely teleport (e.g having Broken Remote and an item that doesn't require to be charged) is another way to get there.

Boss Rush


If the player manages to beat Mom in under 20 minutes from the start of the run (visually indicated by the clock icon that appears during the cutscene between floors), a crack will open in the wall of the Boss Room upon defeating her, allowing entry to a large Room with 2 or 4 item pedestals in the center or the corners, often blocked by rocks or spikes. Taking one of the presented items will destroy the others and begin the Boss Rush.


 * can be used to open the Boss Rush entranceway crack in the Mom Boss Room even after the 20 minute deadline, allowing access to the Boss Rush Room.
 * The Broken Shovel Handle opens the Boss Rush Room, even after the 20 minute deadline. The Trapdoor to the next Floor is also closed until Boss Rush is completed.
 * Mausoleum Mom also spawns the Boss Rush Room if defeated fast enough, having a bigger deadline of 25 minutes.

Mega Satan Arena


This long Room is only found in the starting Room of and. Opening this door requires or the two key pieces from Angels. Once the Room is entered, Isaac will have to face off against Mega Satan.

??? Entrance


If the player manages to beat Mom's Heart or It Lives in under 30 minutes (visually indicated by the clock icon that appears during the cutscene between floors), a crack will open in the wall of the Boss Room upon defeating it, containing a room with a Trapdoor to.

Mother Arena


Mother's arena is accessible by a large pit in the ground in the Boss Room of II. Dropping down into the pit lead's to Mother's unique transforming boss room.

Greed Exit Rooms


Exit Rooms are Rooms with the defining feature of having a Trapdoor/exit to the next Floor.

Greed Exit Rooms start metal barred and unbombable, like miniboss rooms, but will be unbarred and accessible once ten waves of enemies are defeated.
 * Greed Exit Rooms have a special door, having a special black exit doorway in the main greed room, but having a normal floor colored doorframe when in the room itself.

Exit Rooms may contain coins and enemies.

Greedier Exit Rooms
Greedier Exit Rooms are almost exactly the same as the Greed Mode Exit Room, except they take 11 rounds to open.

Alternate Path Exit Rooms
When unlocked, these Rooms appear attached to a Main Path Boss Room once the Boss is defeated (or appear at the end of Alternate Path Chapter). These Rooms contain an entrance to the Alternate Path Floors. These Rooms have different requirements to unlock them, based on the Chapter they are barring entrance to:


 * 1) In floors 1-2, the door requires a key to unlock a chapter 1.5 floor.
 * 2) In floors 3-4, the door requires two bombs to bomb open a chapter 2.5 floor.
 * 3) In floors 5-6, the door requires sacrificing two hearts to enter a chapter 3.5 floor.

A Strange Door Exit Room


When unlocked, this room appears above the starting room of the second floor of Chapter 3, containing a trapdoor leading to a special version of the second floor of Chapter 3.5. This door can only be opened by obtaining and sacrificing either, , or Faded Polaroid.

Closets
Closets are rare, small, dead end Rooms. They will often contain a unique arrangement of items, objects, or pickups.
 * Closets don't have a special Door, but do have a very minutely changed Map Icon, having thicker borders then normal Rooms.

Grave Rooms
Grave Rooms are Rooms that appear in the which only contain 1-3 Dirt Patches. is unlocked by reaching this room and digging with.

Mirror Room
The Mirror Room is a single special room found on the second floor of Chapter 1.5, containing a single mirror on either the left or right doorway location. This mirror can be broken by explosions, but also can be entered to explore the Mirrored World, a replica of the current floor, to find. The mirror can only be entered by, , , and 's ghost form. All other characters must touch the white fire which always generates on the second floor of Chapter 1.5 in order to temporarily become The Lost if they want to enter the mirror.



Mineshaft Room
The Mineshaft Room is a single special room found on the second floor of Chapter 2.5 only if Isaac already has. It contains a Yellow Button, a single minecart, a blocked door at the top of the room and occasionally some enemies.

There are 2 other Yellow Buttons located randomly on the same floor and pressing all 3 repairs the minecart's track allowing access through the blocked door. Alternatively having Flight and 2 bombs also allows access through the door. The area past the blocked door contains and a chase sequence with Mother's Shadow. The door is permanently blocked after leaving the sub-area.