With Microsoft on board, Yu set to work on the XBLA version of Spelunky. The only request from the publisher: Lose the pixel graphics of the freeware version. For Yu, this wasn't a problem.

"That was not really a difficult discussion to have with me because I wasn't interested in just putting the pixel graphics from the original game on Xbox anyway. The way I was thinking was that if I was doing this for Xbox, I [didn't] want to just port the game."

But soon it became clear that Yu's one-man operation simply could not sustain the work of bringing a game to XBLA. In the middle of 2009, he reached out to an old friend, Andy Hull, to take on the major programming duties. The two had known each other for over a decade through various indie development communities, and Hull had just wrapped up work on an interactive storybook, 'What is Bothering Carl.' Hull remembers the two met up at PAX Prime in 2009.

"Derek was telling me he got the XBLA deal and that he'd been trying to work on it by himself but that he really needed a programmer, especially someone that had done a lot of graphics programming. I was just like, 'Well, you know, that's what I did in college. That was my major, essentially. And I just wrapped up my last project, so I'm available.' He was like, 'Sure, let's give it a go.'"

SOON IT BECAME CLEAR THAT YU'S ONE-MAN OPERATION SIMPLY COULD NOT SUSTAIN THE WORK OF BRINGING A GAME TO XBLA.

The pair started work on a prototype of the XBLA version, with a planned development cycle of about nine months. Jonathan Blow had actually offered them the source code and engine of Braid to make the game, but it quickly became clear that it wasn't what they needed.

"At one point Derek called me one night and said, 'I think we need to just do our own engine. You can do that, right?'" Hull was terrified.

"After I graduated college, there was a big gap between college and starting Spelunky," says Hull. "I was actually working as a wooden toy designer for most of it. I had not been programming for a long time. I think working in Jon's code got me reacclimated to programming. It was helpful when we started building our own engine, because I had just been working with someone else's engine, so I had an idea of how I could maybe do some things better than I had done in the past."

As it turned out, the new engine was seriously aided by the freeware version ofSpelunky. "From the get-go, I knew what the engine had to do. It's not a luxury that most people have when they're making a game. In that sense, I was able to make decisions specifically tailored to Spelunky because I knew what the game was going to be about."

"AT ONE POINT DEREK CALLED ME ONE NIGHT AND SAID, 'I THINK WE NEED TO JUST DO OUR OWN ENGINE. YOU CAN DO THAT, RIGHT?'"

Even with the freeware version to guide them, Spelunky's nine-month development cycle soon went out the window. Both Hull and Yu admit that their total lack of console development experience led to a massive underestimation of how long the game would take.

"It very much felt like we were always like six months from being done," says Hull. "We were just naïve in terms of the amount of work that the Xbox functionality required."

Polish was another big factor in the delay, says Hull.

"Derek always said, 'The goal is Nintendo quality.' That sense that you want it to feel as polished and as good as the best Mario game. Whether we get there or not is not really the point. Obviously we'd like to, but it's about always striving to make things feel just right. You just lose a lot of time to that. It takes a lot of time to keep tweaking things to make everything perfect."

Signs of achieved perfection began to begin to appear in early 2012, where the XBLA version of Spelunky went on to win the award for Excellence in Design at the Independent Games Festival.