The Binding of Isaac is a 2011 roguelike action-adventure game designed by independent developers Edmund McMillen and Florian Himsl.

The game was the result of a week-long game jam between McMillen and Himsl to develop a The Legend of Zelda-inspired roguelike that allowed McMillen to showcase his feelings about both positive and negative aspects of religion, which he had come to discover from conflicts between his Catholic and born again Christian family members while growing up.

McMillen had considered the title a risk, but one he could take after the financial success of Super Meat Boy, and released it without much fanfare to Steam in September 2011, not expecting many sales.

Developer Nicalis worked with McMillen in 2014 to complete a remake of the game, The Binding of Isaac: Rebirth, adding features McMillen had planned that exceeded Flash's capabilities, as well as to improve the game's graphics and enable ports for other systems beyond personal computers, including PlayStation 4 and Vita, Xbox One, Wii U, Nintendo 3DS, and the Nintendo Switch.

[1][2][3][4][5][6][7][8] McMillen later worked with James Id to develop The Legend of Bum-bo, which serves as a prequel to The Binding of Isaac.

This is most commonly done by the character's tears as bullets in the style of a twin-stick shooter, but the player can also use a limited supply of bombs to damage enemies and clear out parts of the room.

Until The Binding of Isaac: Repentance expansion in the remake, there is no clear conclusion, or even consistent narrative, to the story past this point.

The first ten endings serve as introductions to unlocked items and mechanics, while the final three suggest meaningful evidence to understanding the conclusion (although this is not revealed until a new game and three DLCs later).

The Binding of Isaac was developed following the release of Super Meat Boy, which McMillen considered a significant risk and a large time effort.

[13] The Binding of Isaac's main concept was the result of a weeklong game jam that McMillen had with Florian Himsl; at the time, his co-contributor on Super Meat Boy, Tommy Refenes, was on vacation.

[12] McMillen also wanted to encourage players to experiment to learn how things work within Isaac, mirroring how Miyamoto had done with the original Zelda game.

[10][17][18] On the story side, McMillen explained that the religious tone is based on his own experiences with his family, split between Catholics and born-again Christians.

[12] He took inspiration from that duality to create Isaac's narrative, showing how religion can both instill harmful feelings while also bringing about dark creativity.

[12] McMillen also considered the scare tactics used by the Christian right to condemn popular media of the 1980s, such as heavy metal and video games.

[12] McMillen said that because they were not worried about sales, they were able to work with Valve to release the game without fears of censorship or having to seek an ESRB rating.

[12] Danny Baranowsky, the game's composer and who previously worked with McMillen on Super Meat Boy, was involved early on with the project shortly after the completion of the first prototype.

Baranowsky had been drawn to The Binding of Isaac as though the game puts forth a dark tone, he stated it had rather silly undertones underneath and such that one could not take it too seriously.

[27][28] Though disappointed with Nintendo's decision, McMillen did not think the loss of the 3DS port was a major issue, and saw a brief sales burst on Steam as the news was covered on gaming websites.

[35] The game introduced numerous new playable characters, items, enemies, bosses, challenges, and room layout seeds for floors.

A content pack, entitled Afterbirth was released for Rebirth starting October 2015, adding new alternate chapters, characters and items, as well as wave-based Greed mode.

McMillen collaborated with James Id to develop The Legend of Bum-bo, which was released on November 12, 2019, for Windows and later for iOS and Switch.

On June 27, 2018, Edmund McMillen announced and later released a card game adaptation in cooperation with Studio 71 titled The Binding of Isaac: Four Souls.

[42][48][45] John Teti for Eurogamer praised the game for its replayability through the randomization aspects, calling it "the most accessible exploration of the roguelike idea" that he had seen.

[42] Edge's similarly commented on the lure to replay the game due to its short playthrough time, calling it "an imaginative and quick-witted arcade experience that manages to be both depraved and strangely sweet by turn".

Club rated the game an A on a grading scale, and favorably compared the title to McMillen's Super Meat Boy, requiring the player to have "masochistic patience in the face of terrible odds".

[44] Neilie Johnson for IGN found that some players may be put off by the game's crudeness but otherwise "it's totally random, highly creative and brutally unforgiving".

[46] Similarly, Nathan Muenier for GameSpy noted the game had some shock value that one must work past, but otherwise was "imaginative" and "utterly absorbing".

[48] Baranowsky's soundtrack was found by reviewers to well-suit the themes of the game, and used appropriately to avoid extensive repetition during a playthrough.

[9][48] Kirk Hamilton of Kotaku called the soundtrack as the combination of several genres and the musical styles of Danny Elfman, Muse, and Final Fantasy that created something "dark and unique".