Edmund McMillen talks new card game Binding of Isaac: Four Souls, and why it's not a videogame

After weeks of teasing, The Binding of Isaac co-creator Edmund McMillen has revealed his latest Isaac venture: a tabletop spin-off called The Binding of Isaac: Four Souls, which launched through Kickstarter on Wednesday and blew past its goal within hours. The dice-and-card game represents a whole new vein of design for the indie creator, making something entirely physical and wholly multiplayer for the first time. As Edmund and his design partner and wife Danielle told me, the game's invention was as much about them having fun creating it as it was anything else.

“I was approached like a year and a half ago and they wanted to license the Isaac IP to make their own game, and I was like 'well no I'm not going to do that, I'd need to design it myself and I don't have any ideas for any kinda board game—if anything comes up I'll let you know!'” Edmund said. About a year later, he was sick one weekend and decided to take a crack at designing an Isaac card game. "I started prototyping some stuff on paper and then once I was feeling better, my wife and I went to a crafts store and got a bunch of index cards and within a week I had a pretty rough prototype that was playable.”

Now that development is essentially finished, the Kickstarter is a way to get mass production off the ground with Studio 71, who’re publishing the game as well as overseeing the bulk of the business side of the campaign. For the first time in Edmund's career, designing a game hasn't been an isolating drudge—sitting in front of a computer with his team over Skype, everyone tapping away in relative silence.

Four Souls required long sessions with multiple players to double-check each new wave of alterations. “It's just 'Hey, I'm going to test my game, I'm going to have a bunch of friends come over, eat pizza and play games all night long once a week every week for six months,'” Edmund said. “It's fun!”

Here's the basic breakdown of Four Souls:

There are three decks. There's the item deck, which contains 100 treasure cards, a mix of items from Binding of Isaac and some new creations. The loot deck makes up the cards you'll have in your hand and draw regularly. Last is the monster deck, "full of bosses and basic monsters and random happenings, like treasure chest rewards or curses."

How do you win? Kill bosses to collect their souls, and the first player to four souls wins the game. The game is currently built for 2-4 players, with the final version expected to support up to six, and sessions generally last from 30 minutes to an hour.

I compare it Munchkin, another card game that's similarly heavy on monster encounters and co-operative play, but Edmund considers it more a melding of Magic: The Gathering and Settlers of Catan, citing the use of a stack-system from the former and reliance on bartering and “alternate win conditions” from the latter. There are a number of characters to choose from, including Maggie, Judas and Isaac himself, each offering some play-modifying ability, and there's the requisite hearts for health and pennies for currency.

During their turn, players can activate item cards from their hand, and can then choose to either buy an item from the store—the top two face-up cards of the item deck—or attack a monster to begin an encounter. The rest of the table can assist or interfere with the right cards, and the turn ends with either the monster or the challenging player dying.

Death isn't quite as big a deal as it is in the roguelike. It's mercifully impermanent, carrying with it a penalty of one item, one discard from your hand, and one penny.

Dice play is a big factor, generating the RNG Isaac's known for. Combat relies on rolling, making every turn that bit more dramatic. “I don't think I appreciated before just how fun it is to roll a dice,” Danielle McMillen said. “And then getting a critical hit with a group of people is like, 'YES!'” 

The current iteration of Four Souls has been rigorously tested, with feedback from Tyler Glaiel, Edmund's collaborator on The End Is Nigh, and George Fan, creator of Plants Vs. Zombies. But it's not completely design-locked just yet. A function of the Kickstarter campaign will be getting feedback from a wider selection of sources.

“As we go, even beyond the Kickstarter, hoping we get what we need, I'm going to be very open about development and show the layouts of cards so we can get feedback,” Edmund said. “I want its design to be as simple as possible without losing depth.” Expect the McMillens to stream play sessions during the campaign, too, to explain the more intricate aspects and demonstrate all the different play-styles one can employ to make things get “very Isaac-y.”

When I interviewed Edmund previously on the ending of The Binding of Isaac, he spoke about the dark period of deep introspection that created The End Is Nigh, his most grim and nihilistic project to date. The Binding of Isaac: Four Souls is, for he and Danielle, the end of the journey that started with that development cycle and a re-kindling of their love of design and game-making. Of course, Edmund hasn't left digital games—he has The Legend of Bum-bo coming later this year—but this was a refreshing change of pace for the McMillens both.

“It was a much, much needed break from the usual bullshit,” Edmund said with a sigh. “The End Is Nigh was so rough. And getting through it and being able to look back on it and being able to appreciate it for what it was and teaching me that it's not just a loss—this was definitely the light at the end of the tunnel.”