The Binding of Isaac is a 2011 roguelike game created by Edmund McMillen and Florian Himsl. It first came out for Microsoft Windows and later was made available for OS X and Linux. The game’s name and story are based on the Bible’s tale of the Binding of Isaac. In the game, Isaac’s mother gets a message from God asking for her son’s life as a test of faith. Isaac runs away to his home’s monster-filled basement to survive. Players control Isaac or one of six other characters as they explore a randomly generated dungeon, similar to games like The Legend of Zelda. They fight monsters in real-time, collect items, and defeat bosses to eventually face Isaac’s mother.
The game was made during a one-week game development event where McMillen and Himsl aimed to create a roguelike inspired by The Legend of Zelda. This allowed McMillen to express his views on religion, which he learned about from conflicts between his Catholic and born-again Christian family. After the success of Super Meat Boy, McMillen released the game on Steam in September 2011 with little promotion. It became popular due to Let’s Play videos. In 2012, the developers released an expansion called "Wrath of the Lamb," but further updates were limited by the Flash platform. Nintendo had agreed to help make a version for the 3DS but later canceled the deal because of the game’s religious themes.
In 2014, developer Nicalis helped McMillen remake the game as The Binding of Isaac: Rebirth. This version added features not possible with Flash, improved graphics, and allowed the game to be played on systems like PlayStation 4, Xbox One, and Nintendo Switch. The remake is often called one of the best roguelike games ever made.
McMillen later worked with James Id to create The Legend of Bum-bo, a game that serves as a prequel to The Binding of Isaac.
The game has received positive reviews for its roguelike design, which encourages repeated play. By July 2014, over 3 million copies had been sold. The game is credited with helping to increase interest in roguelike games among players and developers.
Gameplay
The Binding of Isaac is a game where players explore dungeons from above, using 2D images. In the game, players control Isaac or other characters they can unlock later. These characters have different speeds, health amounts, and damage abilities. The game plays similarly to the dungeons in The Legend of Zelda, but with randomly created levels like those in roguelike games. Each floor of the dungeon has rooms where players must fight monsters before moving forward. Players usually defeat enemies using tears that act like bullets, similar to twin-stick shooters, or by using bombs. As characters gain power-ups, they can use new abilities, such as charging tears by holding a button or shooting tears behind them. Power-ups include items that automatically improve the character's abilities, items that can be used once after completing rooms, and one-time items like pills or Tarot cards that provide temporary benefits. These effects can combine to create strong advantages for the player.
After clearing a room, it stays clear, allowing players to revisit it, but once they move to the next floor, they cannot return. Along the way, players collect money to buy power-ups, keys to unlock treasure rooms, and new weapons. Health is shown as hearts; if all hearts are lost, the game ends, and players must restart from the beginning. Each floor has a boss that must be defeated to progress. On the sixth floor, players fight Isaac's mother; after defeating her, Isaac enters her womb. Later floors are harder, ending with a battle against the heart of Isaac's mother on the eighth floor. An optional ninth floor, called Sheol, includes a boss named Satan. Winning the game with specific characters or under certain conditions unlocks new power-ups or allows players to use other characters. The game keeps a record of all power-ups found, which players can view through the game's menus.
Plot
The story of The Binding of Isaac is based on the biblical tale of the same name. Isaac, a young boy, and his mother live in a small house on a hill. They live quietly and happily, with Isaac drawing pictures, playing with his toys, and his mother watching Christian broadcasts on television.
One day, Isaac's mother hears "a voice from above," which she believes is God. The voice says Isaac is "affected by sin and needs to be saved." It tells her to remove all evil from Isaac, and she agrees. She takes away his toys, drawings, and clothes. The voice speaks again, saying Isaac must be separated from all evil. His mother agrees and locks him in his room. The voice speaks a third time, saying she has done well but asking her to sacrifice Isaac. She agrees, takes a butcher's knife from the kitchen, and goes to Isaac's room. Isaac sees her through a large crack in his door and panics. He finds a hidden trapdoor under his rug and jumps into it just as his mother enters the room. The game begins anew each time after Isaac jumps into the trapdoor.
Before the Repentance expansion in the game's remake, the story has no clear ending or consistent plot beyond this point. The original game includes 13 possible endings, each appearing after a major boss fight. The first ten endings introduce new items and game mechanics, while the final three provide clues about the story's conclusion. However, these clues are only fully explained after playing the game again and completing three extra game content sections.
In two cutscenes during the game, Isaac is shown curled up in a ball, crying. His thoughts are shown on the screen, including feelings of rejection from his mother, embarrassment from others, and a scene involving his death.
Development and release
The Binding of Isaac was created after the release of Super Meat Boy, which McMillen viewed as a risky and time-consuming project. When Super Meat Boy received praise from critics and sold well, McMillen felt confident that his financial risks were supported by its success. He also believed he could take more creative risks with his next project. Originally, McMillen planned to work with Tommy Refenes, a co-developer of Super Meat Boy, on their next game, Mewgenics. However, since Refenes was taking a break, McMillen decided to make a simpler game with lower expectations, such as an Adobe Flash game.
The main idea for The Binding of Isaac came from a one-week game jam with Florian Himsl, who was McMillen’s co-developer on Super Meat Boy at the time. Tommy Refenes was away on vacation during this period. McMillen’s concept had two parts: to create a roguelike game inspired by the dungeon structure of the first The Legend of Zelda game and to explore his thoughts on religion. He was influenced by Shigeru Miyamoto, the creator of the original Zelda games. McMillen saw value in the randomly generated levels found in roguelikes, such as in Spelunky and Desktop Dungeons, and believed this would help develop his planned game, Mewgenics. He compared Isaac’s controls to those in the game Smash TV.
Each floor of the dungeon in Isaac had randomly created rooms. These rooms were chosen from a library of 200 pre-designed layouts, with monsters, items, and other features added. Fixed rooms, like boss rooms and treasure rooms, were also included on each floor. McMillen used the structure of Zelda dungeons to design how players would progress through the game. In Zelda, players gain new items to help them advance, and McMillen applied this idea by ensuring each level in Isaac gave players at least one item and a bonus item after defeating a boss. He also wanted players to experiment with the game’s mechanics, similar to how Miyamoto encouraged exploration in the original Zelda. The game became harder as players progressed, and additional content was added after completing the game to make it feel longer. McMillen designed four characters based on classes from Dungeons & Dragons: fighter, thief, cleric, and wizard.
The story of Isaac reflects McMillen’s family background, which included both Catholics and born-again Christians. He noted that while both groups shared the same Bible, their beliefs and attitudes differed. Some Catholic rituals inspired him, while other beliefs condemned activities he enjoyed, like playing Dungeons & Dragons. This contrast influenced the game’s narrative, which explores how religion can inspire creativity while also causing conflict. McMillen also drew from the scare tactics used by the Christian right in the 1980s, which linked popular media like heavy metal and video games to satanic themes. He connected these ideas to biblical stories, shaping the game’s story around them. He also included humor that was different from what his family approved of, such as toilet jokes, which he had used in earlier games. While Super Meat Boy helped build his reputation, he felt it was a "safe" game in terms of humor. He used Isaac to return to this style, even though it could have been risky for his career.
The Binding of Isaac began as a game jam between McMillen and Florian Himsl. Within a week, they created a working version using Adobe Flash’s ActionScript 2. They decided to complete the game for release on Steam, without expecting high sales. It took about three months of part-time work to finish the game from the prototype. They faced limitations with Flash and ActionScript, but continued using these tools to release the game. Because they were not worried about sales, they worked with Valve to release the game on Steam without fear of censorship or needing an ESRB rating. Steam allowed them to update the game freely, which was not possible on other platforms without high costs. They released the game without extensive testing, as it would have taken many players to test all possible item combinations. A week after the Steam release, McMillen shared a demo version on Newgrounds. Merge Games later produced a physical version of the game, including the soundtrack and a poster, for sale in the United Kingdom in 2012.
Adobe Flash’s ActionScript 2 was outdated and caused performance issues on many computers. It also lacked support for game controllers, so Tommy Refenes helped write a program to unlock Steam achievements. McMillen later said he would not have made the game in Flash if he had known how popular it would become.
Danny Baranowsky, the game’s composer and a previous collaborator with McMillen on Super Meat Boy, joined the project early after the first prototype was completed. McMillen and Baranowsky worked together, with McMillen sharing artwork and allowing Baranowsky to create music based on it. This often led to McMillen creating more art to match the music. Baranowsky was inspired by the game’s dark tone but noted its silly undertones. Some songs were based on classical choral music, while others were inspired by Nobuo Uematsu’s compositions for the Final Fantasy series. Baranowsky also created short tracks for special rooms, like shops and secret areas.
In January 2012, after the game sold over 450,000 copies, McMillen was approached by a publisher interested in releasing it on the Nintendo 3DS through the Nintendo eShop. However, he was hesitant due to Nintendo’s strict content policies. In late February, Nintendo rejected the game because of "questionable religious content." McMillen believed this decision was influenced by Germany’s classification board, which rated the Windows version of the game as "age 16+" due to potentially blasphemous content. This was the first time a game received such a rating in Germany. McMillen noted that Nintendo executives had previously mentioned concerns about the game’s content before the rejection.
Reception
The Binding of Isaac received mostly positive reviews from game critics. On Metacritic, the game has an average score of 84 out of 100 based on 30 reviews.
Reviewers praised the game for its ability to be played many times, thanks to the wide variety of power-ups players can collect during a playthrough. The game is also described as easy to learn, with a structure similar to the classic game Zelda, which most players recognize. John Teti of Eurogamer highlighted the game’s replayability, calling it "the most accessible exploration of the roguelike idea" he had seen. Edge noted that the game’s short playtime encourages players to replay it, calling it "an imaginative and quick-witted arcade experience" that is both "depraved and strangely sweet." GameSpot’s Maxwell McGee said the game removed unnecessary features, leaving a focused and fresh experience even after multiple plays. While the game is easy for new players to understand, reviewers noted that its difficulty comes from the randomness of power-ups players receive during a run. Writers for The A.V. Club gave the game an A grade and compared it to McMillen’s Super Meat Boy, which requires players to have "masochistic patience" due to its challenging odds. This difficulty is lessened by the many power-ups available, most of which players only discover after replaying the game multiple times. McGee noted that while players can review items before a run, the game does not explain what each item does, leaving players to figure out effects during gameplay.
Adam Biessener of Game Informer mentioned that the game had some software bugs at release, but praised the game’s playability, art style, and story. Neilie Johnson of IGN said some players might find the game’s crude style off-putting, but called it "random, creative, and unforgiving." Nathan Muenier of GameSpy noted the game’s shocking content but described it as "imaginative" and "absorbing." Jordan Devore of Destructoid highlighted the game’s dark comedy style, similar to McMillen’s Super Meat Boy. Reviewers also praised the game’s soundtrack, which blends genres and styles from artists like Danny Elfman, Muse, and Final Fantasy to create a "dark and unique" sound. Kirk Hamilton of Kotaku described the soundtrack as combining multiple musical styles effectively.
The Binding of Isaac was nominated for Best Independent Game at the 2011 Spike Video Game Awards but lost to Minecraft.
McMillen expected the game to sell only a few hundred copies when it was released on Steam. For the first few months, sales averaged a few hundred copies per day. Later, sales increased sharply, which McMillen attributed to Let’s Play videos shared by players online. This popularity led to interest in creating custom game modifications, which influenced the design of the sequel to better support modding.
By November 2012, the game had sold over 1 million copies, with at least one-quarter of those purchases including the "Wrath of the Lamb" expansion. By July 2014, sales reached over 3 million copies. By July 2015, after the release of Rebirth, combined sales of the original game and its sequel reached over 5 million copies. The Binding of Isaac is credited with helping the roguelike genre grow in popularity around 2010, inspiring later games like FTL: Faster Than Light and Don’t Starve.