The Binding of Isaac is a 2011 roguelike action-adventure game created by 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 title and story are inspired by 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, fearing for his safety, runs to the monster-filled basement of their home and must fight to survive. Players control Isaac or one of six other unlockable characters as they navigate a randomly generated dungeon, similar to games like The Legend of Zelda. They defeat monsters in real-time battles, collect items, and use power-ups to fight bosses and eventually face Isaac’s mother.
The game was developed during a one-week game jam between McMillen and Himsl. It was designed to reflect McMillen’s views on both positive and negative aspects of religion, influenced by conflicts between his Catholic and born-again Christian family members. McMillen considered the title 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 gained popularity through Let’s Play videos. An expansion called "Wrath of the Lamb" was released in May 2012, but further updates were limited by the Flash platform. Nintendo initially agreed to a 3DS version in 2012 but later canceled the deal 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 added features previously impossible with Flash, improved graphics, and expanded the game to platforms like PlayStation 4, Vita, Xbox One, Wii U, Nintendo 3DS, and Nintendo Switch. The remake is often praised as one of the best roguelike games ever made.
McMillen later collaborated with James Id to create The Legend of Bum-bo, a prequel to The Binding of Isaac. The game has received positive reviews for its roguelike gameplay, which encourages repeated playthroughs. By July 2014, over 3 million copies had been sold. The game is credited with helping to revive interest in the roguelike genre among players and developers.
Gameplay
The Binding of Isaac is a game where players explore dungeons in a two-dimensional, side-view style. Players control Isaac or other characters they can unlock, moving through rooms in Isaac's basement. Each character has different abilities, such as speed, health, and damage power. The game's style is similar to The Legend of Zelda, but its levels are randomly created each time, like games in the roguelike genre. In each room, players fight monsters using tears that act like bullets, or by using bombs. As players gain power-ups—items that automatically improve their abilities—they can also use special skills, such as firing charged tears or shooting behind them. Power-ups include ones that last forever, ones that can be used once after completing rooms, and ones that provide one-time effects, like healing or changing stats. These effects can combine to create strong advantages.
After clearing a room, players can revisit it later, but once they move to the next level, they cannot return. Along the way, players collect money to buy items, 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 dungeon 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 characters. The game keeps track of all power-ups found and lets players view them in the game's menu.
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, with Isaac drawing pictures and playing with his toys while his mother watches Christian television programs.
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 takes away his toys, drawings, and clothes. The voice speaks again, telling her Isaac must be separated from all evil. She agrees and locks him in his room. The voice speaks a third time, asking her to sacrifice Isaac. She agrees, takes a knife from the kitchen, and goes to his room. Isaac sees her through a crack in the door and 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 has 13 possible endings, each after defeating a major boss. The first ten endings introduce new items and game mechanics, while the last three provide clues about the story's conclusion, though these are not fully explained until a new game and three DLCs are played.
In two cutscenes during the game, Isaac is shown curled up, crying. His thoughts are visible, showing feelings of rejection from his mother, embarrassment from others, and a scene where he imagines his own death.
Development and release
The Binding of Isaac was created after the release of Super Meat Boy, which its developer, Edmund 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, who co-created 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, like 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 on vacation during this time. McMillen had two goals: to create a roguelike game based on the dungeon structure from the first The Legend of Zelda game and to make a game that explored his thoughts on religion. He was inspired by Shigeru Miyamoto, the creator of Zelda. McMillen believed that the procedural generation in roguelikes, like in Spelunky and Desktop Dungeons, could help with developing Mewgenics. He compared Isaac’s controls to the game Smash TV.
Each floor of the dungeon in Isaac had randomly generated rooms. These rooms were chosen from a library of 200 layouts, and then monsters, items, and other features were added. Some rooms, like boss rooms and treasure rooms, were fixed and appeared on every floor. McMillen used the structure of Zelda dungeons to design how players would progress. In Zelda, players get new items to help them move forward, so McMillen made sure each level in Isaac had at least one item and a bonus item after defeating a boss. He also wanted players to experiment with the game, like Miyamoto did with Zelda. The game became harder as players progressed, and extra content was added after beating 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 was inspired by McMillen’s family, which includes Catholics and born-again Christians. He noticed differences in how they used the Bible and how they viewed certain activities, like playing Dungeons & Dragons. He used these ideas to show how religion can both inspire creativity and cause harm. He also thought about how the Christian right criticized media from the 1980s, like heavy metal music and video games, and how some stories from the Bible seemed similar to these ideas. McMillen also included humor about unusual topics, like toilet jokes, which his family did not like. While Super Meat Boy helped build his reputation, he 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 started as a game jam between McMillen and Himsl. Within a week, they had a working game made in Adobe Flash using ActionScript 2. They decided to finish the game and release it on Steam, but they did not expect it to sell well. It took about three months of part-time work to complete the game. They faced limits with Flash and ActionScript, but they continued using these tools to release the game. Because they were not worried about sales, they worked with Valve to release it without fear of censorship or needing an ESRB rating. Steam allowed them to update the game freely, which other platforms would not have let them do without extra costs. They did not test the game extensively with many players, as it would have taken too many people to test all the possible item combinations. Instead, they relied on buyers to help test the game. A week after releasing it on Steam, McMillen shared a demo version on Newgrounds. Merge Games later released a physical version of the game with a soundtrack and poster in the UK in 2012.
ActionScript 2 was an old program that caused some computers to slow down. It also did not support controllers, so Tommy Refenes helped create a program for Steam achievements. McMillen later said he would not have made Isaac in Flash if he had known how popular it would become.
Danny Baranowsky, the game’s composer and someone who worked with McMillen on Super Meat Boy, joined the project early. He and McMillen worked together, with McMillen sharing artwork and Baranowsky creating music based on it. This often led to McMillen making more art to match the music. Baranowsky said the game had a dark tone but also silly elements that made it less serious. Some songs were inspired by classical choral music, while others were based on boss fight music from Final Fantasy. After finishing the main music, Baranowsky added short tracks for special rooms like shops and secret areas.
In January 2012, after selling over 450,000 copies, McMillen was approached by a publisher interested in bringing Isaac to the Nintendo 3DS. However, he was unsure because Nintendo usually avoids content that is too risqué. In late February, Nintendo rejected the game due to “questionable religious content.” McMillen believed this was because Germany’s classification board rated the Windows version of the game as “age 16+” due to potentially blasphemous material, the first time a game received that rating in the country. He noted that Nintendo executives had previously mentioned concerns about blasphemous content before the decision.
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 described the game as having high replayability because of the many different power-ups players can collect during a playthrough. These power-ups combine in unique ways, making each game experience different. The game also uses a familiar structure inspired by the Zelda series, which helps players understand how to play. John Teti of Eurogamer praised the game for its replayability, calling it "the most accessible exploration of the roguelike idea" he had seen. Edge magazine noted that the game’s short playtime and creative design made it fun to play again and again. 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 noted it is challenging due to the randomness of power-ups players receive. 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. McGee explained that players can see what items they have discovered before a playthrough, but the game does not explain what each item does, leaving players to figure it out during gameplay.
Adam Biessener of Game Informer mentioned that the game had some software bugs when it was first released, but these did not affect the overall quality of the game’s playability, art, and story. Neilie Johnson of IGN said some players might find the game’s style too crude, but others would enjoy its randomness, creativity, and difficulty. Nathan Muenier of GameSpy said the game had surprising elements that players needed to get used to, but it was imaginative and engaging. Jordan Devore of Destructoid called the game’s visual style one of its strongest features, similar to McMillen’s earlier work on Super Meat Boy. Reviewers also praised the game’s soundtrack, which combined different music styles from artists like Danny Elfman, Muse, and Final Fantasy to create a dark and unique sound. Kirk Hamilton of Kotaku said the music helped avoid repetition during gameplay.
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. At first, sales were about a few hundred copies each day, but sales increased suddenly after players shared "Let’s Play" videos online, which showed others how to play the game. This popularity led to players creating custom modifications for the game, which influenced the design of the sequel to support more 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 copies. The Binding of Isaac is credited with helping the roguelike genre grow in popularity around 2010. Its success inspired later games that used the roguelike formula, such as FTL: Faster Than Light and Don’t Starve.