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Basement55.png

The Basement is the first floor of Chapter 1 in The Binding of Isaac, which takes the appearance of an unfinished basement, that possibly has brick walls. The monsters "indigenous" to the chapter are Flies.

Rooms

  • 1: The room will always appear once in this floor
  • 2: The room will always appear twice in this floor
  • Possible: There is a chance for this room to appear, usually due to certain criteria being met
  • *: This room can only appear due to a bug or special item
  • -: The room cannot appear in this floor


Rooms with the core game
Rooms Basement 1 Basement 2 Basement XL Note
Regular Rooms 7 - 11 13 - 14 21-25 The player must have Wrath of the Lamb installed for The Basement XL to appear.
Treasure room icon.png Treasure Room 1 1 2
Shop icon.png Shop 1 1 1 There is always one shop (except in The Womb / Utero), even in XL floors.
Secret room icon.png Secret Room 1 1 1
BossRoomIcon.png Boss Room 1 1 2 Boss Rooms are always linked in XL floors.
Challegne room icon.png Challenge Room Possible Possible Possible Will only be generated if Isaac has full health while entering the floor.
Arcade icon.png Arcade - Possible - Only generated when Isaac has 5 or more Coins upon entering a new floor or part.
Super secret room icon.png Devil Room * Possible Possible *Only reachable by The Joker card.
Super secret room icon.png I AM ERROR Possible Possible Possible Only reachable by using the Telepills, which have a 6.66% chance to teleport Isaac to this room.
Rooms with Wrath of the Lamb
Rooms Basement 1 Basement 2 Basement XL Note
Super secret room icon.png Super Secret Room 1 1 1
Curse room icon.png Curse Room Possible Possible Possible
Sacrifice room icon.png Sacrifice Room Possible Possible Possible
Angel room icon.png Angel Room * Possible Possible *Only reachable by The Joker card.
Libary icon.png Library Possible Possible Possible 5% base chance to spawn, 25% if Isaac is holding a book.
Boss challenge room.png Boss Challenge Room * Possible Possible Can spawn on The Basement 1, probably due to a bug.

Monsters

Monster Description WotL DLC
Black Fly
Fly.png
Tiny black flies that do not hurt Isaac upon touch.
Attack Fly
CUSTOMredfly.png
Red Flies that follow Isaac and deal touch damage.
Moter
Moters.png
Follows Isaac, similar to Attack Flies. Will split into 2 Attack Flies upon death.
Eternal Fly
White fly.png
Invulnerable Fly that sticks to corny poop Nuttypoop.png, Holy Leeches Holy leech.png, Hangmans Hang man.png, Psychic Maws Psychicmaw.png, rarely Mr. Maws Shape4336.png and very rarely Maws Maws.png.
Pooter
Pouter.png
Moves slowly around, shooting 1 projectile at Isaac when he gets near.
Sucker
Sucker.png
Flies slowly towards Isaac, exploding into 4 projectiles in a + formation upon death.
Mulligan
Mulligan.png
Harmless enemy that walks around the room, avoiding Isaac. Will spawn multiple fliesFly.png upon death.
Mulligoon
Mulligoon.png
Harmless enemy that walks around the room, avoiding Isaac. Will drop a Troll BombTroll bomb.png upon death.
Hopper
Hopper.png
Jumps around the room slowly, damaging Isaac by touch.
Flaming Hopper
FHopper.png
Jumps around the room quickly, covering a large distance, similar to Trites.Spider hopper.png
Pacer
Pacer.png
Walks aimlessly around the room. Usually spawned after killing a Gaper/Frowning Gaper.Gaper.png
Gusher
Gusher.png
Walks aimlessly around the room, firing extremely short-ranged blood projectiles from its head. Usually spawned after killing a Gaper/Frowning Gaper.Gaper.png
Gaper
Gaper.png
Walks towards Isaac, dealing contact damage. Usually turns into a PacerPacer.png or GusherGusher.png upon death.
Frowning Gaper
Frowninggaper.png
Walks towards Isaac, dealing contact damage. Usually turns into a PacerPacer.png or GusherGusher.png upon death.
Horf
Horfs.png
Stationary enemy that fires medium ranged blood shots at Isaac.
Clotty
Clotty.png
Moves around the room, firing 4 blood shots in a plus pattern.
Clot
Clot2.png
Moves around the room, firing 4 tar shots in an X pattern.
I. Blob
Blockade.png
Moves around the room, firing 8 shots in all directions.
Bosses found in normal rooms:
Embryo
Embryo.png
Aimlessly hops around the room, damaging Isaac by contact damage.

Bosses

Notes

  • Locked treasure rooms cannot spawn on Basement 1 unless it is the XL version of it.
  • A Challenge Room cannot spawn on Basement 1. However, Boss Challenge Rooms can.
  • A devil room or Angel Room cannot spawn on The Basement 1, but you can teleport there.
  • An Arcade cannot spawn on The Basement 1.
  • There will be no tutorial if you spawned in a XL floor.

Room-layouts

Related Achievements

Spider.jpg The Radioactive Spider - Complete The Basement once.
Monstrostooth.jpg Monstro's Tooth - Defeat all of the bosses in The Basement. (Duke of Flies, Monstro, Gemini, Larry Jr.)
Basementboy.jpg Basement Boy - Complete The Basement without taking damage.

Chapters
Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6

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