Developed by Super Meat Boy designer Edmund McMillen, the indie hit was released for PC and Mac in September 2011.
Speaking to IndieGames, McMillen described the title's success as "ridiculous", adding that "there's no reason for this game to have done well".
He continued: "When I started development on Isaac, I wasn't even sure if I should charge for it, because I didn't think people would want it, in all honestly.
"I had to shop it around to a bunch of different developers, and say like 'Do you think I could sell this?', because I thought it was way too weird, I thought the content was too disturbing and creepy.
"I thought it would just rub too many people the wrong way and I thought the design was just too hardcore for any kind of mass amount of people to enjoy."
The Binding of Isaac's success has led to the development of 'The Wrath of The Lamb' expansion pack, which is expected to be released in the near future.
> 'Binding of Issac' being considered for 3DS
Watch a trailer for The Binding of Isaac below: