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Basement55

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 Treasure Room 1 1 2
Shop icon Shop 1 1 1 There is always one shop (except in The Womb / Utero), even in XL floors.
Secret room icon Secret Room 1 1 1
BossRoomIcon Boss Room 1 1 2 Boss Rooms are always linked in XL floors.
Challegne room icon Challenge Room Possible Possible Possible Will only be generated if Isaac has full health while entering the floor.
Arcade icon Arcade - Possible - Only generated when Isaac has 5 or more Coins upon entering a new floor or part.
Super secret room icon Devil Room * Possible Possible *Only reachable by The Joker card.
Super secret room icon 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 Super Secret Room 1 1 1
Curse room icon Curse Room Possible Possible Possible
Sacrifice room icon Sacrifice Room Possible Possible Possible
Angel room icon Angel Room * Possible Possible *Only reachable by The Joker card.
Libary icon Library Possible Possible Possible 5% base chance to spawn, 25% if Isaac is holding a book.
Boss challenge room Boss Challenge Room * Possible Possible Can spawn on The Basement 1, probably due to a bug.

Monsters[]

Monster Description WotL DLC
Black Fly
Fly
Tiny black flies that do not hurt Isaac upon touch.
Attack Fly
CUSTOMredfly
Red Flies that follow Isaac and deal touch damage.
Moter
Moters
Follows Isaac, similar to Attack Flies. Will split into 2 Attack Flies upon death.
Eternal Fly
White fly
Invulnerable Fly that sticks to corny poop Nuttypoop, Holy Leeches Holy leech, Hangmans Hang man, Psychic Maws Psychicmaw, rarely Mr. Maws Shape4336 and very rarely Maws Maws.
Pooter
Pouter
Moves slowly around, shooting 1 projectile at Isaac when he gets near.
Sucker
Sucker
Flies slowly towards Isaac, exploding into 4 projectiles in a + formation upon death.
Mulligan
Mulligan
Harmless enemy that walks around the room, avoiding Isaac. Will spawn multiple fliesFly upon death.
Mulligoon
Mulligoon
Harmless enemy that walks around the room, avoiding Isaac. Will drop a Troll BombTroll bomb upon death.
Hopper
Hopper
Jumps around the room slowly, damaging Isaac by touch.
Flaming Hopper
FHopper
Jumps around the room quickly, covering a large distance, similar to Trites.Spider hopper
Pacer
Pacer
Walks aimlessly around the room. Usually spawned after killing a Gaper/Frowning Gaper.Gaper
Gusher
Gusher
Walks aimlessly around the room, firing extremely short-ranged blood projectiles from its head. Usually spawned after killing a Gaper/Frowning Gaper.Gaper
Gaper
Gaper
Walks towards Isaac, dealing contact damage. Usually turns into a PacerPacer or GusherGusher upon death.
Frowning Gaper
Frowninggaper
Walks towards Isaac, dealing contact damage. Usually turns into a PacerPacer or GusherGusher upon death.
Horf
Horfs
Stationary enemy that fires medium ranged blood shots at Isaac.
Clotty
Clotty
Moves around the room, firing 4 blood shots in a plus pattern.
Clot
Clot2
Moves around the room, firing 4 tar shots in an X pattern.
I. Blob
Blockade
Moves around the room, firing 8 shots in all directions.
Bosses found in normal rooms:
Embryo
Embryo
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 The Radioactive Spider - Complete The Basement once.
Monstrostooth Monstro's Tooth - Defeat all of the bosses in The Basement. (Duke of Flies, Monstro, Gemini, Larry Jr.)
Basementboy Basement Boy - Complete The Basement without taking damage.

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

The ChestWrath of the Lamb DLC

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