The Basement

Lore & Background

The story sets up the descent in a short sequence. Isaac and his mother live in a small house on a hill. After the voice tells her to sacrifice her son, she takes a butcher's knife from the kitchen and walks to his room; Isaac, watching through a crack in the door, finds a trapdoor under his rug and jumps in just as she bursts through the door. Every new run is taken to begin just after that jump. Rebirth, the 2014 remake, keeps the same premise: Isaac escapes to the basement as his mother is about to kill him and fights through random, roguelike dungeons. During the original game's cutscenes between floors, Isaac is shown curled up in a ball, crying, his thoughts ranging from rejection by his mother to humiliation by his peers.

Reader's Guide

The original game has eight main floors. On each one the player must clear a room of monsters before moving on to the next, mostly by firing Isaac's tears like bullets, with a limited supply of bombs to damage enemies and open up parts of a room. Once a room is cleared it stays clear, so the player can retrace their steps on a floor, but there is no going back once they descend. Each floor ends with a boss. Isaac's mother is fought on the sixth floor; after she is beaten, Isaac crawls into her womb, and the later floors get much harder, ending with a fight against her heart on the eighth. An optional ninth floor, Sheol, holds Satan. In Rebirth each floor also contains special rooms such as treasure rooms, shops, mini-boss fights, dice rooms, arcades, vaults, planetariums and curse rooms.

Did You Know?

• Isaac escaped into the basement through a trapdoor hidden under the rug in his room.
• Random rooms for each floor were built by picking ten to twenty rooms from a library of 200 layouts, then adding monsters and items, plus fixed rooms such as a boss room and a treasure room.
• The dungeon structure was modelled on the first The Legend of Zelda, with McMillen making sure every floor offered at least one item.