The Binding of Isaac is a 2011 roguelike action-adventure game created by independent developers Edmund McMillen and Florian Himsl. It was first released for 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 her 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. They explore a dungeon that changes each time the game is played, similar to games in The Legend of Zelda series. Players defeat monsters in real-time battles, collect items and power-ups, and eventually face Isaac’s mother.
The game was created during a one-week game jam where McMillen and Himsl aimed to make a roguelike inspired by The Legend of Zelda. This project allowed McMillen to express his thoughts about both positive and negative aspects of religion, which he learned from conflicts between his Catholic and born again Christian family members. McMillen believed the game’s title was risky but decided to release it on Steam in September 2011 after the success of his earlier game, Super Meat Boy. He expected few sales but the game became popular, partly due to Let’s Play videos shared online. In May 2012, McMillen and Himsl released an expansion called "Wrath of the Lamb." However, they could not expand further because of limits in the Flash platform. They had begun working with Nintendo to make a version for the 3DS, but Nintendo stopped the project due to concerns about the game’s religious themes.
In 2014, developer Nicalis partnered with McMillen to remake the game as The Binding of Isaac: Rebirth. This version included features McMillen had planned but could not add earlier, improved graphics, and supported additional platforms such as PlayStation 4 and Vita, Xbox One, Wii U, Nintendo 3DS, and the Nintendo Switch. This remake is often considered 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 game has received positive reviews, with critics praising its roguelike design, which encourages repeated playthroughs. By July 2014, McMillen reported that over 3 million copies had been sold. The game is credited with helping to increase interest in the roguelike genre among players and developers.
Gameplay
The Binding of Isaac is a game where players explore dungeons from an overhead view, using two-dimensional images called sprites. Players control Isaac or other characters they can unlock later. These characters have different speeds, health amounts, and damage abilities. The game’s style is similar to The Legend of Zelda, but its levels are randomly created each time, like in roguelike games.
Each floor of the dungeon has rooms where players must fight monsters before moving forward. Players usually attack with tears that act like bullets, similar to twin-stick shooters. They can also use bombs, but only a limited number. As characters gain power-ups, they gain new abilities. Power-ups are items players automatically wear when picked up. These can improve attributes like health or tear strength, or add effects like firing charged tears after holding a button or shooting tears behind the character. Power-ups include passive items that improve attributes automatically, active items that can be used once and recharged by completing rooms, and single-use items like pills or Tarot cards that give one-time benefits, such as restoring health or changing attributes. These effects can combine for strong advantages.
After clearing a room, it stays clear, letting players 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 special rooms, and new weapons. 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, has a boss named Satan. Winning the game with certain characters or under specific conditions unlocks new power-ups or allows players to use other characters. The game keeps a record of all power-ups found, which can be viewed through its menus.
Plot
The story of The Binding of Isaac is loosely based on the biblical tale of the same name. In the game, Isaac, a young boy, and his mother live in a small house on a hill. They keep to themselves, 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 from above," which she believes is God. The voice tells her that Isaac is "affected by sin and needs to be saved." It asks her to remove all evil from Isaac, and she agrees, taking away his toys, drawings, and even his clothes. The voice speaks again, saying Isaac must be separated from evil things. His mother agrees and locks him in his room. The voice speaks a third time, questioning her devotion and telling her to sacrifice her son. She agrees, takes a butcher's knife from the kitchen, and goes to Isaac's room to carry out the act. Isaac, seeing his mother through a crack in his door, becomes frightened. He finds a hidden trapdoor under his rug and jumps into it just as his mother enters the room. It is believed that each new game begins right after Isaac jumps into the trapdoor.
Before the Repentance expansion in the game's remake, the story has no clear ending or consistent narrative 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 hints about the story's conclusion. However, these hints are not fully explained until a new game and three DLCs are completed.
In two levels of the game, Isaac is shown curled up in a ball, crying. His thoughts are visible and include feelings of rejection from his mother, humiliation 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 saw as a big risk and a lot of work. When Super Meat Boy received praise and sold well, McMillen felt he could take financial risks because its sales supported him. He also wanted to take more creative risks with his next project. He had planned to work with Tommy Refenes, a co-developer of Super Meat Boy, on their next game, Mewgenics. However, since Refenes was taking time off, McMillen decided to make a game with lower stress and fewer 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-contributor on Super Meat Boy at the time. Tommy Refenes was on vacation during this time. McMillen’s plan had two parts: to make a roguelike game based on the dungeon structure from the first The Legend of Zelda game and to create a game that explored his thoughts on religion. He was inspired by Shigeru Miyamoto, the creator of the original Zelda games. McMillen saw the value in procedural generation, a feature in games like Spelunky and Desktop Dungeons, and believed it would help develop 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 layouts, and then monsters, items, and other features were added. Fixed rooms, like a boss room and treasure room, were also included on each floor. McMillen used the structure of Zelda dungeons to design how players would progress. In Zelda, players gain new items to help them advance, and McMillen applied this idea by ensuring each level in Isaac had at least one item and one bonus item from defeating a boss. He also wanted players to experiment and learn how the game worked, similar to how Miyamoto designed the original Zelda. The game became harder as players progressed, and new content was added after completing the game to make it feel longer. Four of the playable characters in Isaac were based on classes from Dungeons & Dragons: fighter, thief, cleric, and wizard.
On the story side, McMillen explained that the religious themes came from his family’s experiences, which included both Catholics and born-again Christians. He noted that while both groups shared the same Bible, their beliefs differed. He found some Catholic rituals inspiring but other beliefs condemning of activities he enjoyed, like playing Dungeons & Dragons. He used this contrast to create Isaac’s story, showing how religion can both inspire creativity and cause harm. McMillen also referenced how the Christian right in the 1980s used scare tactics to criticize media like heavy metal and video games. He noted that some films from that time featured satanic cults and that these stories mirrored biblical tales, which influenced Isaac’s narrative. He also included humor about unusual topics, like toilet jokes, which his family disapproved of. While Super Meat Boy helped build his reputation, McMillen felt it was a “safe” game in terms of humor. He used Isaac to return to his preferred style, even though it could risk his career.
The Binding of Isaac began as a game jam between McMillen and Florian Himsl. In one week, they created a working game using Adobe Flash’s ActionScript 2. They decided to finish it as a game they could release on Steam, with no expectations for 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. McMillen said that because they were not worried about sales, they could work with Valve to release the game without fear of censorship or needing an ESRB rating. Releasing through Steam allowed them to update the game freely, which they could not do on other consoles without high costs. They did not do extensive testing with players because it would have taken hundreds of users to test all possible item combinations. Instead, they released the game and let buyers act as playtesters. 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.
At the time, ActionScript 2 was an outdated program that caused some computers to run slowly. It also did not support controller use, and Tommy Refenes helped write a program to allow players 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 made. McMillen and Baranowsky worked together, with McMillen sharing artwork and letting Baranowsky create music based on it. This often led to McMillen making more art to support the music. Baranowsky said the game had a dark tone but also silly undertones that made it less serious. Some songs were inspired by classical choral music, while others were influenced by boss fight music from the Final Fantasy series by Nobuo Uematsu. Baranowsky also created short tracks for special rooms like shops and secret areas after finishing the main music.
In January 2012, after the game sold over 450,000 copies, McMillen was approached by a publisher interested in releasing it on Nintendo 3DS through the Nintendo eShop. 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 decision was influenced by Germany’s classification board, which rated the Windows version of the game as “age 16+” because of 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 blasphemous 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 from 30 reviews.
Reviewers described the game as fun to play again and again because of the many different power-ups players can collect during a playthrough. The game’s design is similar to Zelda, a well-known game series, making it easy for most players to understand. John Teti from Eurogamer praised the game for its replayability, calling it "the easiest way to experience roguelike gameplay." Edge noted that the game’s short playtime encourages players to replay it, calling it "imaginative and quick-witted" with a mix of dark and sweet elements. GameSpot’s Maxwell McGee said the game removed unnecessary features, leaving a focused experience that stays fresh even after many playthroughs. Though the game is easy for new players to learn, reviewers found it challenging because of 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, noting it requires "patience in the face of difficult odds." The game’s difficulty was balanced by the large number of power-ups, many of which players might not see until they replay the game multiple times. McGee noted that while players can review items before a playthrough, the game does not explain what each item does, leaving players to discover effects during gameplay.
Adam Biessener from Game Informer mentioned the game had some software bugs at launch that briefly affected the experience, but praised the game’s playability, art style, and story. Neilie Johnson from IGN said some players might find the game’s crude style off-putting, but called it "random, creative, and very challenging." Nathan Muenier from GameSpy noted the game had a shocking style that players needed to get past, but called it "imaginative" and "engaging." Jordan Devore from Destructoid highlighted the game’s dark comedy style, similar to McMillen’s earlier work in Super Meat Boy. Reviewers also praised the game’s soundtrack, which combined music from different genres and artists like Danny Elfman, Muse, and Final Fantasy, creating a "dark and unique" sound. Kirk Hamilton from Kotaku called the soundtrack a mix of styles that fit the game’s themes well.
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 were about a few hundred copies per day. Later, sales increased suddenly, which McMillen attributed to player-made videos that showcased the game and attracted more buyers. This popularity led to players creating custom mods for the game, a feature that influenced the design of the sequel to support modding.
By November 2012, the game had sold over one million copies, with at least one-quarter of those purchases including the "Wrath of the Lamb" expansion. By July 2014, the game had sold over 3 million copies. By July 2015, after the release of Rebirth, the combined sales of both games reached over 5 million units. The Binding of Isaac is considered to have helped grow the roguelike genre since around 2010, inspiring later games like FTL: Faster Than Light and Don’t Starve.