Red Key

Effects

• Allows Isaac to create a (Red Room) Red Room by using it next to a wall where there would be no conditions that could prevent a room from spawning there (i.e., the same conditions for a (Secret Room) Secret Room to spawn). This is indicated by red door outlines on walls.
• These rooms are most commonly normal rooms, but have a 10% chance to be a special room instead, even including Red (Devil Room) Devil Rooms or (Angel Room) Angel Rooms.
  • Red special rooms of any kind can appear in every floor.
• These rooms use a special Red Room icon on the map.

Notes

• The types of special rooms that a (Red Room) Red Room can be are the following:

• (Angel Room) Angel Room

• (Arcade) Arcade

• (Clean Bedroom) Clean Bedroom

• (Curse Room) Curse Room

• (Devil Room) Devil Room

• (Dice Room) Dice Room

• (Dirty Bedroom) Dirty Bedroom

• (Library) Library

• (Mini-Boss Room) Mini-Boss Room

• (Planetarium) Planetarium

• (Sacrifice Room) Sacrifice Room

• (Secret Room) Secret Room

• (Shop) Shop

• (Super Secret Room) Super Secret Room

• (Treasure Room) Treasure Room

• (Vault) Vault

• All rooms made by Red Key will be 1x1 rooms that can have doors available on all sides (same conditions as a (Secret Room) Secret Room / (Super Secret Room) Super Secret Room).

• In (Home) Home, Isaac can create a "Red Room" on the left side of the map right under Mom's room. This room will actually be a closet containing a non-tainted character's Tainted form.

  • If the respective Tainted character has already been found or a Tainted character is played, the room will contain Inner Child instead. If Inner Child has not been unlocked, the room will contain a Shopkeeper.

• If a door created by Red Key takes Isaac outside of the 13x13 area of the floor, he will be taken to the (I AM ERROR) I AM ERROR room.

  • This does not occur in (Corpse) Corpse II, (Dark Room) Dark Room, (Chest) Chest, (The Void) The Void, or the special version of (Mausoleum) Mausoleum / (Gehenna) Gehenna II containing Dad's Note. No door outlines will appear at any boundary walls.
    • Additionally, this doesn't work during the Red Redemption challenge.
  • The I AM ERROR room door can only be created while already inside a Red Room. Normal rooms will not show the red outline if they are at the map's boundary.

• Red (Shop) Shops will regularly not offer items from the Shop item pool for sale, but instead draw from Boss and Treasure Room pools instead. Additionally, Red Shops have a chance to become advanced Shops with many more items for sale, akin to (Tainted Keeper) Tainted Keeper's better Shops.

• Red Key can't overwrite (Secret Room) Secret Rooms or (Super Secret Room) Super Secret Rooms. This can be used to discern their locations by finding walls that don't have red door outlines that would otherwise be valid Red Room spots.

• Red Key can't create a room adjacent to the (Boss Room) Boss Room on most floors, with some exceptions:

  • Red Key can create a room adjacent to Hush's room in the top right where the room that leads to (The Void) The Void usually generates. The door to this looks like a crack. This Red Room can only be created when Isaac is in another Red Room adjacent to it, i.e. from branching off one of the (Treasure Room) Treasure Rooms.
    • Isaac can enter Hush's room from this crack, but going the other direction will lead him to the Entrance Portal room.
    • Strangely, Isaac also can't create Red Rooms adjacent to the (Shop) Shop on this floor either.
  • Red Key can create rooms adjacent to most Boss Rooms in (The Void) The Void, including Delirium's room. This can be used to find a Boss Room door leading to what would be an empty space (though this may find Mr. Fred instead).
  • Red Key can create rooms adjacent to the (Boss Room) Boss Room in the Mirrored World of (Downpour) Downpour / (Dross) Dross II.

• When Isaac enters any Red Room adjacent to the (Ultra Secret Room) Ultra Secret Room, it immediately appears on the map along with the Secret Room jingle, and its door will automatically open.

• If Isaac encounters a Red special room, all of its doors will be its special theme doors.

  • All doors in a Red (Curse Room) Curse Room still feature spikes, which will damage Isaac if he decides to enter/exit.
  • A Red (Vault) Vault's doors or a Red (Dice Room) Dice Room's doors each require two keys to open. The door where Isaac uses Red Key will be automatically unlocked, but the other doors remain locked until Isaac goes through them from inside or unlocks them from outside.

• Multiple Red special rooms of the same type can spawn on one floor.

• All Red (Sacrifice Room) Sacrifice Rooms will have their own independent use counters and rewards.

• If Isaac has a teleport to a specific room ((XVII - The Stars) XVII - The Stars, (IX - The Hermit) IX - The Hermit, Teleport 2.0, etc.) and has created a special room such that there are multiple of a certain type on one floor, the teleport will choose randomly between each room.

  • However, if Isaac has found a Red (Planetarium) Planetarium, XVII - The Stars will always teleport Isaac to it over any (Treasure Room) Treasure Rooms.

• It is possible to obtain Knife Piece 1 and Knife Piece 2 outside of the intended methods by spawning Treasure Rooms that contain them.[citation?needed]

• In (Downpour) Downpour / (Dross) Dross II, if Isaac enters a Red Room after touching the White Fire Place and becoming (The Lost) The Lost, he will still be The Lost in every Red Room, but will change back to his regular form when entering a normal room.

  • Red Rooms in Downpour/Dross can contain White Fire Places as well.

• Isaac is able to create Red Rooms in the Mirrored World of (Downpour) Downpour / (Dross) Dross II. They will be reflections of the original floor's Red Rooms, and special rooms created in this way will still be empty.

• Red Rooms can't be created around the (Mine Cart Room) Mine Cart Room of (Mines) Mines / (Ashpit) Ashpit II.

  • Red Rooms on these floors can contain the yellow buttons used to build the mine cart track, however these ones do nothing.

• Red Rooms in Chapter 3 can contain Marked Skulls even before the Ascent is unlocked.

• When in (Dark Room) Dark Room or (Chest) Chest, their spawn room containing their respective chests can be created by Red Key. These will function as regular chests of their respective type.

  • New Mega Satan doors can't be found in these rooms.

Synergies

• Book of Virtues: Creates a Red Key wisp in the middle ring. The wisps have a chance to unlock Red Rooms when Isaac enters an unexplored room.
• (Broken Glasses) Broken Glasses / (Devil's Crown) Devil's Crown / More Options / (Pay to Win) Pay to Win: Affects Red (Treasure Room) Treasure Rooms.
• Glowing Hour Glass: Rewinding out of a Red Room and creating it again in the same place will generate a new one, potentially a better one.
• (Judas' Tongue) Judas' Tongue / (Keeper's Bargain) Keeper's Bargain / (Number Magnet) Number Magnet / A Pound of Flesh / Sanguine Bond: Affects Red (Devil Room) Devil Rooms.
• Luna: Affects Red (Secret Room) Secret Rooms and (Super Secret Room) Super Secret Rooms.
• Mama Mega!: Will trigger its effect in new Red Rooms, provided it has already been used on the floor.

Interactions

• 4.5 Volt: Usually generates fewer than 1 charge per room, as Red Rooms are always 1x1.
• Member Card: The trap door will always lead to the same special room as the regular (Shop) Shop.
• Void: Won't adquire any of the Red Key's properties.