The Binding of Isaac is a 2011 game created by independent developers Edmund McMillen and Florian Himsl. It was first released for computers running Microsoft Windows, and later made available for OS X and Linux. The game’s name and story are based on the Biblical tale of the Binding of Isaac. In the game, Isaac’s mother receives a message from God asking for her son’s life as a test of faith. Isaac, afraid for his life, runs to the monster-filled basement of their home, where he must fight to survive. Players control Isaac or one of six other characters who can be unlocked. The game uses a randomly generated dungeon, similar to The Legend of Zelda, where players defeat monsters in real-time battles, collect items, and eventually face Isaac’s mother.
The game was created during a one-week game development event where McMillen and Himsl aimed to make a roguelike game inspired by The Legend of Zelda. This project allowed McMillen to express his views on both positive and negative aspects of religion, which he learned about from conflicts between his Catholic and born again Christian family members. McMillen believed the game’s title could be risky, but he decided to release it after the success of his earlier game, Super Meat Boy. He launched the game on Steam in September 2011 with little promotion, expecting few sales. However, the game became popular after many players shared gameplay videos online. In May 2012, McMillen and Himsl released an expansion called "Wrath of the Lamb." They could not expand further due to technical limits of the Flash platform. They had begun working with Nintendo to create a version for the 3DS, but Nintendo canceled the plan because of the game’s religious themes.
In 2014, developer Nicalis helped McMillen remake the game as The Binding of Isaac: Rebirth. This version included features McMillen had planned but could not add before, improved the game’s visuals, and made it available on platforms like PlayStation 4 and Vita, Xbox One, Wii U, Nintendo 3DS, and the Nintendo Switch. This remake is often called one of the best roguelike games ever made.
Later, McMillen worked with James Id to create The Legend of Bum-bo, a game that serves as a prequel to The Binding of Isaac.
The Binding of Isaac has received positive reviews from critics, who praise its roguelike design, which encourages players to try the game many times. By July 2014, McMillen reported that over 3 million copies of the game had been sold. The game is credited with helping to increase interest in the roguelike genre among both players and game developers.
Gameplay
The Binding of Isaac is a two-dimensional game where players control Isaac or other characters as they explore dungeons in Isaac's basement. Each character has different abilities, such as speed, health, and damage. The game's style is similar to The Legend of Zelda, but it also includes randomly created levels like those found in roguelike games. On each floor of the dungeon, players must fight enemies in a room before moving forward. Players usually attack by shooting tears, like in a twin-stick shooter, or use bombs to damage enemies. As players gain power-ups—items that automatically improve their abilities—they can unlock new ways to defeat enemies, such as firing charged tears or shooting behind them. Power-ups include items that improve abilities permanently, 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, creating strong combinations of abilities.
After clearing a room, players can return to it later, but once they move to the next floor, they cannot go back. Along the way, players can collect money to buy items, keys to unlock treasure rooms, and new weapons or power-ups. Health is shown by 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, and 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, features a boss named Satan. Winning the game with certain characters or under specific conditions unlocks new power-ups or the ability to play as other characters. The game keeps track of all power-ups collected and allows players to review them 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 enjoy their own company, with Isaac drawing pictures and playing with his toys while his mother watches Christian broadcasts on television.
One day, Isaac’s mother hears a voice she believes is from God. The voice says Isaac is "filled with sin and needs to be saved." It tells her to remove all evil from Isaac, and she agrees, taking away his toys, drawings, and clothes. The voice speaks again, telling her Isaac must be separated from all evil in the world. His mother agrees and locks him in his room. The voice speaks a third time, questioning her devotion and telling her to sacrifice Isaac. She agrees, takes a butcher’s knife from the kitchen, and goes to Isaac’s room. Isaac, seeing her through a crack in his door, panics. He finds a hidden trapdoor under his rug and jumps inside just as his mother enters. The game begins anew each time after Isaac jumps into the trapdoor.
Before the Repentance expansion in the remake, the story has no clear ending or consistent plot beyond this point. The original game includes 13 possible endings, one after each major boss fight. The first ten endings introduce new items and game mechanics, while the final three provide clues about the story’s conclusion, though these clues are not fully explained until a new game and three DLCs are completed.
In two levels of the game, Isaac is shown curled up, crying. His thoughts are visible, including feelings of rejection from his mother, being teased by others, and imagining his own death.
Development and release
The Binding of Isaac was created after the release of Super Meat Boy, which McMillen saw as a big risk and a lot of work. When Super Meat Boy was well received by critics and sold well, McMillen felt more confident about taking financial risks. He also thought he could take more creative risks with his next project. He had planned to work with Tommy Refenes, the co-creator 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-creator on Super Meat Boy at the time. Tommy Refenes was on vacation during this time. McMillen had two goals: to make a roguelike game inspired by the dungeon structure of the first The Legend of Zelda game and to explore his thoughts about religion. He was influenced by Shigeru Miyamoto, the creator of the original Zelda games. McMillen saw the value in procedural generation, a feature found in games like Spelunky and Desktop Dungeons, which he believed would help with his planned game Mewgenics. He compared Isaac’s controls to 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-built layouts, and then monsters, items, and other features were added. Each floor also included fixed rooms, such as a boss room and a treasure room. McMillen used the structure of Zelda dungeons to guide how players would progress through the game. In Zelda, players gain new items to help them advance, and McMillen included similar mechanics in Isaac, ensuring each level had at least one item and a bonus item from defeating a boss. He wanted players to experiment and learn how the game worked, just as Miyamoto did in the original Zelda. The game became harder as players progressed, and new content was added after completing the game to make it feel longer. McMillen designed four characters based on the main classes of Dungeons & Dragons: fighter, thief, cleric, and wizard.
The story of Isaac was inspired by McMillen’s family experiences, which included both Catholics and born-again Christians. He noticed differences in how each side interpreted the Bible and how some beliefs conflicted with his interests, like playing Dungeons & Dragons. He used these contrasts to create Isaac’s story, showing how religion can cause both harm and creativity. McMillen also drew from the scare tactics used by the Christian right in the 1980s to criticize media like heavy metal and video games. He noted that some propaganda films from that time featured satanic cults and child sacrifices, which he connected to Bible stories. He also included humor that his family found unusual, such as toilet jokes, which he had explored in earlier games. While Super Meat Boy helped build his reputation, McMillen felt it was a safer game in terms of humor. He used Isaac to return to his preferred style, even though it could be risky for his career.
The Binding of Isaac began as a game jam between McMillen and Florian Himsl. In one week, they created a working prototype using Adobe Flash’s ActionScript 2. They decided to finish the game and release it on Steam without expecting high sales. It took about three months of part-time work to complete the game from the prototype to the final version. They faced limitations with Flash and ActionScript but continued using these tools to release the game. Since they were not worried about sales, they worked with Valve to release the game without fear of censorship or needing an ESRB rating. Steam allowed them to update the game freely, which they could not do on other platforms without high costs. They released the game without significant 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 released a physical version of the game, including the soundtrack and a poster, in the United Kingdom in 2012.
ActionScript 2 was an outdated program that caused slow performance on many computers. It also did not support 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 much people would care about Isaac.
Danny Baranowsky, the game’s composer and a previous collaborator on Super Meat Boy, joined the project early after the first prototype was made. McMillen and Baranowsky worked together, with McMillen sharing artwork and allowing Baranowsky to create music based on it. This often led to McMillen making more art to support the music. Baranowsky was drawn to Isaac’s dark tone but noted it had silly elements that made it less serious. Some songs were inspired by classical choral music, while others were influenced by Nobuo Uematsu’s boss fight music from 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 bringing Isaac to the Nintendo 3DS as a downloadable title. However, he had concerns because Nintendo typically avoids content that is too risqué. In late February, Nintendo rejected the game due to “questionable religious content.” McMillen believed this was linked to Germany’s classification board rating the Windows version of the game as “age 16+” because of potentially blasphemous content, a first for the country. He noted that Nintendo executives had previously mentioned concerns about blasphemous material in the game.
Reception
The Binding of Isaac received mostly good reviews from game critics. On Metacritic, the game has an average score of 84 out of 100 based on 30 reviews.
Reviewers described the game as having high replayability because players can encounter many different power-ups that combine in various ways during a playthrough. The game’s design is easy to understand, similar to the style of the classic game Zelda. John Teti from Eurogamer praised the game’s replayability, calling it "the easiest way to experience a roguelike game" he had seen. Edge noted that the game’s short playtime makes it fun to replay, calling it "imaginative and clever" with a mix of dark and sweet elements. GameSpot’s Maxwell McGee said the game removed unnecessary features, leaving a focused and fresh experience even after many playthroughs. While the game is easy for new players to learn, reviewers found it challenging due to the randomness of power-ups players receive. 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 be patient despite difficult odds. This difficulty was balanced by the large number of power-ups available, many of which players only see after replaying the game multiple times. McGee noted that players can review items before a playthrough, but the descriptions of these items are not explained, leaving players to discover their effects during the game.
Adam Biessener from Game Informer mentioned that the game had some software bugs at release, but the game’s playability, art style, and story were still strong. Neilie Johnson from IGN said some players might find the game’s rough appearance off-putting, but it is creative and very challenging. Nathan Muenier from GameSpy noted the game had surprising content that players needed to get past, but it was imaginative and engaging. Jordan Devore from Destructoid called the game’s visual style one of its main strengths, similar to McMillen’s earlier work in Super Meat Boy. Reviewers praised Baranowsky’s soundtrack for matching the game’s themes and avoiding repetition. Kirk Hamilton from Kotaku described the soundtrack as a mix of different music styles, including those of Danny Elfman, Muse, and Final Fantasy, creating a dark and unique sound.
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 suddenly, which McMillen attributed to Let’s Play videos created by players that showcased the game. This popularity led to interest in creating custom mods for the game, a feature later included in the sequel to 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" add-on. By July 2014, the game had sold over 3 million copies. By July 2015, after the release of Rebirth, combined sales of both games reached over 5 million copies. The Binding of Isaac helped make roguelike games more popular around 2010, influencing later games like FTL: Faster Than Light and Don’t Starve.