In early 2017, Edmund McMillen was on the verge of releasing a new update for The Binding of Isaac, the designer's weird and gross Zelda-inspired roguelike loosely inspired by the upsetting religious experiences of his upbringing. What started as an experiment became an unexpected hit, and over time, took its toll. He wanted to move on. Back then, McMillen told me this was an effort to "close the book on [Isaac]." That was over four years ago, and last week, McMillen released a new update, Repentance, for The Binding of Isaac.
"I guess a lot happened," laughed McMillen during a recent interview.
McMillen has always been a prolific creator. He started his career releasing literally dozens of Flash-based games online in the space of only a few years. He's used to being quick, dirty, and moving on to the next idea. The one exception to that rule has been The Binding of Isaac, a game whose original development was so rushed and haphazard because of its game jam origins that a few years after its 2011 release, it was literally remade under the moniker Rebirth because there was no way for the original to be ported.
Quite reasonably, Rebirth could have been the end of the road, a way to clean the game up and move on, but McMillen had more ideas and it kept getting more popular. This became the cycle in the years that followed for a game originally made while one of his previous collaborators, Super Meat Boy programmer Tommy Refenes, was on vacation. The Binding of Isaac developed a hugely dedicated community. At one point, that community followed a trail of hints from McMillen and started digging a hole in the ground in search of answers.
Prior to Rebirth, The Binding of Isaac received a major expansion, Wrath of the Lamb. That expansion was rolled into Rebirth in 2014. In 2015, the next big expansion arrived, Afterbirth. Two years later, in 2017, came Afterbirth+. This was the last time I spoke with McMillen, when he was publicly declaring that his time with this world was finally coming to an end. Importantly, Afterbirth+ came with official modding tools. The community could take over.
"I'm in the minority group of how I want to play the game," he told me at the time, "so it's not even abiding by my rules anymore."
By then, McMillen could no longer keep track of everything in the game, stuff he'd come up with! He was forced to reference a fan wiki, and it felt like the game had gotten beyond him. But then Afterbirth+ was released into the world, and things got more complicated.
The Binding of Isaac is beloved, with tens of thousands of "overwhelmingly positive" reviews on Steam for every piece of content that's ever been made for it. Except for Afterbirth+, which was widely panned by the community as making the beloved game worse. What was supposed to be McMillen's escape hatch was now looked at by the community with scorn.
In retrospect, McMillen admits it "did not live up to my standards."
"I was going through a situation where I wasn't able to put my hands in it as much as I used to," he said. "I just handed off some designs and hoped for the best. And it wasn't."
McMillen has been publicly vague about what was so tumultuous during the development of Afterbirth+, only telling Waypoint it was a combination of "legal issues, personal life issues, and just a general depression that came from falling away from friends and industry folk." The expansion was also being made around the same time his first child was born.
This period "got dark," according to McMillen, who admitted he has trouble precisely explaining why the period was so personally overwhelming and impacted Afterbirth+.
"But all I can say is people are fucked up and I dropped like a rock," he said.
Part of emerging from the other side was, in his mind, fixing Afterbirth+. What he didn't know was this process might enable him to say goodbye, because this endeavor would eventually partner him with someone who understood his own game better than he did.
The-Vinh Truong almost didn't play The Binding of Isaac. Truong wasn't a fan of Super Meat Boy, the hardcore platformer McMillen had worked on prior, so why play the new game? But one of Truong's friends insisted he check out The Binding of Isaac. It would change his life.
"I have a bit of an obsession with items and power ups in games," said Truong. "I have a tendency to look up like what every item does and how I can use it. Every game that has a ton of different items that lets you play the game in different ways. That really speaks to me."
(With Repentance, the number of items in The Binding of Isaac now shoots past 700.)
When The Binding of Isaac was released in 2011, Truong was 20 years old and became obsessed. Not only did The Binding of Isaac have tons of items to discover and play with, but the items interacted with one another in weird ways, and the roguelike structure meant every playthrough was different. Typically, Truong would play until he'd exhausted all it had to offer, and suddenly, here was a game designed to never stop offering new experiences.
"I just kept playing it over and over again," he said.
It was a game that didn't just make sense to Truong—it spoke to him. And when he saw a group of fans hack the game in its early days to add their own items—a project called Community Remix—a light bulb went off. Why couldn't Truong be one of those people, too?
When Rebirth came out, Truong figured out how to use a disassembler that would allow him to pry open The Binding of Isaac's core, learn how it all worked, and make it into his own.
"At first, I didn't really want to do anything huge, I just wanted to make a couple simple items," said Truong. "And then, of course, I couldn't stop."
If that mentality sounds familiar, it's because that's how McMillen operates, too.
This project required help, so some of Truong's online friends joined in. Now, the tinkering had become a sprawling mod, filled with not just new items but enemies, levels, and bosses.
"We wanted to show we could make something that could pass as an official thing," he said.
A big problem for Truong and his friends, however, was that their expansion, called Antibirth, was a hack of Rebirth, the remake of The Binding of Isaac. It would not work with Afterbirth, the upcoming official expansion to the game, but it was easy for fans to swap between the two. The release of Afterbirth came and went, and work on Antibirth continued. (For the record, you're not the only person confused by all these similar-sounding names.) The new deadline became the release of Afterbirth+, which would add formal modding tools into the game and make their custom hacking unnecessary.
“It's weird to say I don't want to overstay my welcome here because it's been 10 fucking years, but I personally want to move on to other things.”
Antibirth arrived on December 20, 2016 to much hooplah. It was, in many ways, celebrated in the same way a formal expansion was—vindication for Truong's original goal. This was weeks before the arrival of Afterbirth+, which, as you'll remember, was not celebrated.
"We got very excited because, of course, there were people going around, like going, 'Oh, Antibirth, is better than Afterbirth+!'" said Truong. "And we were like, "Yeah, yeah! Finally we did better than them!" But really, that's not the point. That was never supposed to be the point—we just wanted to make something cool."
Maybe. It sounds like it was some of the point, but regardless, it got McMillen's attention.
"There are some unspoken rules in the Isaac universe that they got right and they didn't cross over," said McMillen.
It got enough of McMillen's attention that he reached out to Truong, and the two started talking about how they could collaborate. What's notable about McMillen wanting to collaborate on design with another person is that he's been typically territorial over that.
"I've been a very rigid design Nazi when it comes to all of my work for forever," he said. "And I just wouldn't let anybody touch it. I just have to have the last say."
Immediately, discussion of a larger project, which would become Repentance, started. But Truong was given a test: collaborate on a booster pack, a series of free upgrades for the poorly received Afterbirth+ to make fans happier, with McMillen. It went well, so McMillen made it harder: work on the final booster pack by yourself. That also went well. It was particularly affirming for Truong, who often reacted to ambitious ideas pitched by McMillen as validation of similar ideas he's been thinking about. They were on the same wavelength.
"He got me to basically loosen up," said McMillen.
Truong theorizes one reason the two creatively clicked so fast is because of their shared experiences growing up. The Binding of Isaac, in which a religious zealot of a mother comes to believe her son is corrupted with sin, deeply resonated with Truong on a thematic level.
"My mom is very religious," said Truong, "and I had to deal with some of the things you usually have to do when you have a really strict religious Asian mom who wants you to be better than everyone else at school. [...] It's a game with very personal feelings."
"I'm not aware of how I communicate, but I've been told I'm not good at it," said McMillen. "It's one of my major flaws. In my head, I just assume that other people know exactly what's going on and I don't have to break things down into bits and pieces. And I guess a lot of things are unsaid when it comes to a lot of my work."
McMillen is not a programmer—he's a designer. It means McMillen is frequently relying on others to implement his ideas, and sometimes, things are lost in translation. He has an eye for detail, but because he's often juggling so many ideas, some of those details are lost.
Truong, however, never forgets. One of the long-running conversations in The Binding of Isaac community is about the changes that were made during the transition into Rebirth from the original Flash version of the game. Some believe the Flash version was harder—and better. Some miss tiny graphical details. A regular conversation between Truong and McMillen during the first year of production on Repentance was Truong asking about differences between the two versions of the game, learning if the changes were deliberate.
"He went through and recorded playing the Flash game at 60 frames-a-second and then was like, "This is why the game was harder." All these examples [where he would say] "The Flash game was harder because this, this, this, this and this and these elements weren't ported over in Rebirth. Did you want me to [change] that?' [pause] And I'm like, yes, I do. [laughs]"
Just a month ago, for example, Truong noted that the Flash version of The Binding of Isaac had a small custom shadow underneath the boss sprites during the screen that appears before Isaac actually has to fight the boss. In Rebirth, there's a generic circle underneath.
"I forgot I added that," said McMillen.
"They're just tiny things that most people wouldn't notice, but add up, really," said Truong.
Other tiny things have added up over the last 10 years, too. McMillen parted ways with the composer of the game's original celebrated soundtrack, Danny Baranowsky, for reasons that still haven't been made public. A scathing report about the game's publisher (and development partner), Nicalis, outlined how the company poorly treated its development partners and its founder, Tyrone Rodriguez, casually used racial and homophobic slurs among employees, claiming they were all jokes.
Nicalis, however, is the contractual partner for The Binding of Isaac. McMillen said it would not collaborate on other projects with Nicalis, but the partnership remained for Repentance.
"I’ve said it publicly many times, Nicalis holds the license for Repentance so it needs to be published by them period," said McMillen on Twitter earlier this year, in response to a fan asking about the relationship. "In the year+ since the issues appeared Tyrone has appeared to clean up his act and I have checked in with his team many different times to make sure."
McMillen now has two children, and his mother, whose parenting influenced The Binding of Isaac, lives with his family again. She moved in after a COVID-19 outbreak where she lived.
“I wonder if I'm taking this too far. I wonder if this will upset the wrong people. I wonder if what I'm saying, even though it's honest and true to my own personal experience, I wonder if I'm taking this a little too far.”
"She's staying with us and re-experiencing and re-understanding situations when it comes to parents and children and having kids," said McMillen. "It's an impossible thing to explain to somebody who's never had kids what it's like to have kids and be a father. It's just utterly impossible. And you get these missing pieces of the puzzle and you start realizing where your parents were at and why certain things happened and why they didn't happen and all these different complicated social interactions that aren't spoken, that are just there when you're a father or a mother or living life—or being poor for that matter. Growing up poor and [realizing] what that does to a family, especially eventually a single mother."
His oldest daughter, Peach, appears to grasp what her father does for a living. She hasn't played The Binding of Isaac, but frequently asks to watch someone else play it. Because so much of the game's themes are abstract, he's unsure what she makes of it. She hasn't said.
When I spoke with McMillen, Repentance was almost done. There were a few more weeks before the launch at the end of the month, and just days before, McMillen had asked the game's current composer, Matthias Bossi, to add something "really specific" to a music track meant to push people's buttons. It's hard to remember, but The Binding of Isaac was controversial, especially when McMillen considered porting the game. Nintendo, for a time, outright rejected the idea of a port onto their platforms. The company later changed its mind.
"[Truong] was like, 'Oh, I hope this doesn't cause issues like getting it on Nintendo [platforms]" or one of those things," said McMillen. "And just hearing him say that just made me remember the development of the original game where I said [to myself] "I wonder if I'm taking this too far. I wonder if this will upset the wrong people. I wonder if what I'm saying, even though it's honest and true to my own personal experience, I wonder if I'm taking this a little too far." And it felt dangerous and exciting and it felt like that again."
When I last wrote about The Binding of Isaac and the possibility of McMillen saying goodbye to the game, my last line was "I'm skeptical." I still am, no matter what McMillen tells me.
But the plan is sound. Release Repentance, launch a Kickstarter for his second Binding of Isaac card game, and spend the next two years making the long-gestating Mewgenics, a game concept McMillen has been kicking around in one for nearly a decade now. After that, the hope is to start making and releasing small games every few months, like the old days.
The thing is, The Binding of Isaac was a small game once. And then it wasn't.
"I have to put Isaac in a little box, push him in the closet and leave him there for a little while," he said. "It's weird to say I don't want to overstay my welcome here because it's been 10 fucking years, but I personally want to move on to other things, because I can't grow as a designer unless I do that and I'm getting to that point where, of course, I love working on Isaac. But I just don't want to be the guy who just walks on one game for his whole life."