Dungeon

Lore & Background

Edmund McMillen's idea for the game was two-fold: a roguelike built on the dungeon structure of the first The Legend of Zelda, and a game about his thoughts on religion. He had been inspired by Shigeru Miyamoto and saw the potential of the procedural generation used in Spelunky and Desktop Dungeons. Random rooms for each floor were made by choosing ten to twenty rooms from a pre-built library of 200 layouts, adding monsters, items and other features, and then including fixed rooms found on every floor, such as a boss room and a treasure room. Following the Zelda model, where the player gets a new item that helps them progress, McMillen made sure every floor had at least one item plus a bonus item for beating the boss. Floors were designed to get harder as the player progressed, with extra content opening up after the game was beaten.

Reader's Guide

On each floor the player must clear a room of monsters before moving on, mainly by firing the character's tears like bullets in the style of a twin-stick shooter, with a limited supply of bombs for damaging enemies and clearing parts of a room. Cleared rooms stay clear, so the player can retrace their path through a floor, but once they descend they cannot return. Each floor has a boss. On the sixth of eight floors the player fights Isaac's mother, after which Isaac crawls into her womb; the later floors are significantly harder and end with a fight against her heart on the eighth floor, with an optional ninth floor, Sheol, holding Satan.

Health is tracked in hearts and the game uses permadeath: lose them all and the run ends, with the next run starting in a freshly generated dungeon. In Rebirth the levels are generated from a random seed, which can be shared so that several people can try the same layout, and each floor contains special rooms such as treasure rooms, shops, mini-boss fights, dice rooms, arcades, vaults, planetariums and curse rooms. The Wrath of the Lamb expansion added alternate floors with harder enemies and a different set of bosses.