The Basement

 

(chapter 1)

Stage ID
1     19

Floor ID
1, 2     1

The Basement is one of the environments in Chapter 1. Unlocked at the beginning of the game, it is considered the easiest of the environments in the game.

The Basement's harder unlockable variants are The Cellar and the Burning Basement.

Monsters

Entity	ID	Description
Frowning Gaper	10.0	Walks towards Isaac, dealing contact damage. Upon getting near Isaac, it will open its eyes and pursue Isaac faster. Usually turns into a Pacer or a Gusher upon death.
Gaper	10.1	Walks towards Isaac, dealing contact damage. Usually turns into a Pacer or a Gusher upon death.
Gusher	11.0	Walks aimlessly around the room, occasionally firing a short ranged blood shot.
Pacer	11.1	Walks aimlessly around the room.
Horf	12.0	Stationary enemy that fires a medium-ranged blood shot at Isaac when he gets in range of them.
Pooter	14.0	Slow-moving fly that occasionally fires single blood shots at Isaac. Does not deal touch damage.
Super Pooter	14.1	An alternate version of the Pooter that fires 2 shots in a V-formation and does not deal touch damage.
Clotty	15.0	Randomly wanders around the room, firing 4 blood shots in the cardinal directions.
Clot	15.1	Randomly wanders around the room, firing 4 tar shots in the ordinal directions.
I.Blob	15.2	Randomly wanders around the room, firing 8 shots in all directions.
Mulligan	16.0	Walks around the room, avoiding Isaac. Upon death, spawns several flies, which can be Flies, Attack Flies or Pooters. Can suicide to explode and launch four projectiles in the cardinal directions while still releasing flies.
Mulligoon	16.1	Walks around the room, avoiding Isaac. Upon death, spawns a Troll Bomb and fires four shots in the ordinal directions. Can suicide to explode, spawn a Troll bomb, and launch eight projectiles in all directions.
Mulliboom	16.2	Chases Isaac and explodes upon death or upon touching Isaac. The explosion deals a half-heart of damage instead of the regular full heart.
Attack Fly	18.0	Red fly that follows Isaac and deals touch damage.
Hopper	29.0	Slowly hops around the room, doing touch damage. Can turn into a Flaming Hopper by jumping into fire.
Flaming Hopper	54.0	Quickly hops around the room, doing touch damage. Covers a larger distance than the regular Hopper.
Sucker	61.0	Flies slowly towards Isaac, exploding into 4 shots in the cardinal directions upon death.
Embryo	77.0	Aimlessly hops around the room, dealing contact damage.
Moter	80.0	Follows Isaac, similar to Attack Flies. Splits into 2 Attack Flies upon death.
Spider	85.0	Erratically moves towards Isaac and deals touch damage.
Nest	205.0	Walks around the room, avoiding Isaac while spawning Spiders. Spawns a Big Spider or a Trite upon death.
Baby Long Legs	206.0	Runs away from Isaac and frequently spawns Spiders.
Small Baby Long Legs	206.1	Runs away from Isaac and occasionally spawns Sacks.
Crazy Long Legs	207.0	Chases Isaac, dealing touch damage. Occasionally stops to spit 8 blood shots in all directions.
Small Crazy Long Legs	207.1	Chases Isaac, dealing touch damage. Occasionally stops to spit 4 blood shots in the diagonal directions.
Fatty	208.0	Slowly walks towards Isaac. Occasionally farts, which pushes Isaac and adjacent enemies away.
Blubber	210.0	Walks around aimlessly and randomly spews a cluster of blood shots in all directions. Has a chance to turn into a Half Sack when killed.
Pale Fatty	210.1	Slowly walks towards Isaac. Occasionally farts and shoots 6 blood shots in all directions. Has a chance to turn into a Blubber upon death.
Level 2 Fly	214.0	Flies toward Isaac erratically, dealing touch damage.
Level 2 Spider	215.0	Crawls around the room erratically, following Isaac and dealing touch damage. Can jump small distances.
Dip	217.0	Slowly dashes in random directions, dealing contact damage.
Brownie Corn	217.2	Quickly dashes in random directions, dealing contact damage.
Wall Hugger	218.0	Moves around the room like Guts, damaging Isaac by contact. Cannot be destroyed.
Squirt	220.0	Dashes towards the player and deals contact damage. Spawns 2 Dips upon death.
Ring Fly	222.0	Gathers with any other Ring Flies in the room. These flies orbit around themselves while following Isaac.
Skinny	226.0	Slowly walks towards Isaac, leaving short-lasting Red Creep behind itself.
Nerve Ending	231.0	Static enemy which acts as a meat shield.
Wall Creep	240.0	Crawls along walls to try to line up with Isaac and shoots three blood shots in a line.
Round Worm	244.0	Pops out of the ground in random locations and spits a blood shot at Isaac if he is in sight.
Psychic Horf	248.0	Stationary enemy that fires a homing shot at Isaac when he gets in range of them.
Full Fly	249.0	Flies toward Isaac erratically, dealing touch damage. Releases 6 bullets in all directions upon death.
Ticking Spider	250.0	Crawls around the room erratically, following Isaac and dealing touch damage. Can jump small distances. Explodes upon death.
Dart Fly	256.0	Flies towards Isaac and attempts to mimic his movements. Deals contact damage.
Conjoined Fatty	257.0	Slowly walks towards Isaac. Occasionally pauses to fart out a line of damaging Green Creep towards Isaac. Chance to turn into a regular Fatty upon death.
Roundy	276.0	Pops out of the ground in random locations, creating a small rock wave. Fires an explosive Ipecac shot at Isaac if he is in sight.
Swarm Fly	281.0	Follows Isaac in large groups and deals contact damage.
Cyclopia	284.0	Walks towards Isaac, dealing contact damage and leaving behind a short-lasting trail of damaging Red Creep. Occasionally shoots a blood shot towards Isaac.
Ulcer	289.0	Pops out of the ground in random locations and spawns a Dart Fly if Isaac is in sight. Fires a blood shot after spawning 6 Dart Flies.
Blue Gaper	297.0	Walks towards Isaac, dealing contact damage.
Greed Gaper	299.0	Walks towards Isaac, dealing contact damage.
Stoney	302.0	Chases Isaac and blocks tears, but does not deal contact damage. Temporarily pauses in exhaustion after a certain amount of time. Invulnerable; dies when the room is cleared.
Ministro	305.0	Hops towards Isaac, occasionally spitting out a cluster of disorganized shots.
Portal	306.0	Spawns various enemies from the current floor until it either vanishes or is killed.

Degraded Bosses
Blastocyst (small)

Bosses

Dingle	The Duke of Flies	Gemini	Gurglings

Larry Jr.	Monstro	The Fallen	Famine

The Headless Horseman	Steven	Dangle	Little Horn

Rag Man	Turdlings	Baby Plum

Unlockable Achievements

• 

  Monstro's Tooth - Beat chapter 1.

• 

  Something From The Future - Beat The Basement 40 times.

• 

  The Cellar - Beat all The Basement bosses (not restricted to beating bosses in The Basement).

• 

  Sprinkler - Beat chapter 1 without taking damage.

• 

  Basement Boy - Beat chapter 1 without taking damage.

Music

The music for the Basement is titled Diptera Sonata. Diptera is the order of true flies. Thus, Diptera Sonata literally means "Fly Sonata".

Binding of Isaac: Rebirth OST