Basement

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 theme of the Basement is flies and poop.

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

After A Secret Exit is unlocked, a locked door similar to the one leading to a Treasure Room will appear in this floor's Boss Room upon defeating the boss, which leads to Downpour / Dross. Like a Treasure Room, this door requires a key to be unlocked. Unlike Angel Rooms and Devil Rooms, this door never disappears.

Monsters

Entity	ID	Description Lua error in Module:Table at line 39: bad argument #1 to 'pairs' (table expected, got nil).
Brownie Corn	217.2	Quickly dashes in random directions, dealing contact damage.
Dart Fly	256.0	Flies towards Isaac and attempts to predict his movements. Deals contact damage.
Swarm	281.0	Follows Isaac in large, tightly-clustered 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.
Blue Gaper	297.0	Walks towards Isaac, dealing contact damage.
Greed Gaper	299.0	Walks towards Isaac, dealing 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.
Suction Pitfall	291.1	Invulnerable and stationary enemy which sucks Isaac towards itself. Isaac falls into it when walked over, taking damage and popping back out after a short delay.
Rag Man's Ragling	246.1	Quickly leaps towards Isaac and deals contact damage. Randomly shoots two purple shots that orbit around it.
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.
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.
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 around randomly and hop towards Isaac when he gets close, 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.
Army Fly	868.0	Chases Isaac, moving along the cardinal directions. Forms a line with other Army Flies in the room. Deals contact damage.
Bulb	61.5	Flies in erratic, angled movements toward Isaac if his active item has charges; on contact, they drain up to 2 charges, but never deal contact damage. If he has no active item, or no charges, they wander around the room aimlessly.
Swarm Spider	884.0	Very erratically hops toward Isaac in large groups, dealing contact damage.
Needle	881.0	Pops out of the ground and lunges towards Isaac, dealing contact damage.

Degraded Bosses:

Name	ID	Notes
Blastocyst	74.0	Small-form only

Bosses


Dingle	The Duke of Flies	Gemini	Steven


Larry Jr.	Monstro	Gurglings	Famine


The Fallen	Headless Horseman	Dangle	Little Horn


Turdlings	Rag Man	Baby Plum

Trivia

The Basement's backdrop consists of an unfinished wooden basement in a relatively good condition, with a mostly clean floor without visible planks, unlike the Cellar and the Burning Basement.