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Chapters are sets of floors which contain similar enemies, themes, bosses, and difficulties. Earlier chapters are divided into two floors, while later chapters contain one floor. Each chapter has different environments which, while retaining the same feel, have slightly different themes, enemies, bosses, and difficulties. Each environment also has its own music.
|The Basement||The Cellar||Burning Basement|
|The Caves||The Catacombs||Flooded Caves|
|The Depths||Necropolis||Dank Depths|
|The Womb||Utero||Scarred Womb|
Chapter 4.5 (Optional)
|The Chest||Dark Room|
For the technical details of how each level / floor is generated, see Level Generation.
|Chapter 1||Chapter 2||Chapter 3||Chapter 4||Optional||Chapter 5||Chapter 6||Endgame|
|The Basement||The Caves||The Depths||The Womb|
|The Cellar||The Catacombs||Necropolis||Utero||???||The Void|
|Burning Basement||Flooded Caves||Dank Depths||Scarred Womb|
|The Basement||The Caves||The Depths||The Womb||Sheol||The Shop||Ultra Greed|
|The Binding of Isaac: Rebirth|
|Achievements||Attributes||Bosses||Cards and Runes||Challenges||Chapters|