Unless you hung about on Newgrounds, odds are you didn't hear about Edmund McMillen until Super Meat Boy and Indie Game: The Movie.
That was the developer's first 'mainstream' hit, after he had slaved away on some 30 projects. And upon that project launching in 2010, McMillen decided to make something a bit different - something that would appeal to a smaller group of people and prove that he hadn't sold out.
"I just wanted to make a randomly generated game based on the Zelda dungeon structure that was also a shooter," he tells PCGamesInsider.biz.
"And I wanted the game's theme to talk about my relationship with religion growing up.
"I also wanted to make it not as accessible as my previous game, Super Meat Boy. I wanted to make a 'cult game' - something a small group of die-hards would love but wouldn't do well.
"Somehow it became my most popular games by far."
This being something of a middle finger project that was meant to prove McMillen's indie cred, the developer initially planned to release the game in a way that stands as a stark contrast to Super Meat Boy appearing on the Xbox Live Arcade page on launch.
"I was actually going to just release it as a flash game for free and get it sponsored," says McMillen, who spoke to Adult Swim among other companies ahead of the game's launch.
"I only spent three months on it so I didn't need much money to make up for the time spent."
I also wanted to make it not as accessible as my previous game, Super Meat Boy. I wanted to make a 'cult game' - something a small group of die-hards would love but wouldn't do well. Somehow it became my most popular games by far.
But ultimately, the game maker opted to release The Binding of Isaac in a slightly more traditional way. After sending an early build to fellow Indie Game The Movie star Jonathan Blow, McMillen was urged to try and launch the game on Steam.
The timing was serendipitous as Valve had just relaxed - perhaps fatefully - its platform.
"Ater shopping it around I was convinced to ask steam if they would publish it, and they did," McMillen says.
There are numerous reasons why The Binding of Isaac became popular but arguably the biggest was another case of serendipitous timing: the streaming boom. Roguelikes have become been particularly popular with streamers and YouTube personalities as there's a great level of replayability there.
In fact, streaming was a large contributing factor to the game's success - early on, The Binding of Isaac wasn't exactly doing gangbusters but after it was picked up by some Let's Players, sales picked up. In fact, the game has sold in excess of seven million copies on Steam alone.
But asked why he thinks the game has been successful, McMillen is somewhat stumped.
"I'm really not sure, he says.
"I think it may be as simple as that it's very replayable and super odd."
Following its early success, indie publisher Nicalis reached out to McMillen saying they should collaborate. What emerged was a total rewrite of the game called The Binding of Isaac Rebirth. Since then, McMillen and co have added to the game with the Afterbirth and Afterbirth+ expansions, as well as with Booster Packs of new content.
In short, gamers absolutely love The Binding of Isaac, which is a large part in the developer and publisher supporting the game for as long as they have. The last Booster Pack launched in May 2018
"People won't stop playing it and constantly want more," McMillen says. "And I also kinda love working on it."
When you think about it, it's pretty incredible that a game that was made initially in two weeks, released after three and one that was nearly given away for free on the internet ended up being supported for seven whole years.
Asked what he has learnt during this time, McMillen's answer is simple: "People like weird shit."