Via Kotaku:

In October of 2009, Urquhart [Obsidian’s CEO] got an interesting call. It was Greg Kampanis, a vice president of content at South Park Digital Studios, the interactive branch of South Park. He said that Matt Stone and Trey Parker—South Park’s co-creators, writers, directors, and voice actors—wanted to make a video game, and they wanted to meet with Obsidian to talk about it.

“I said, ‘Sure, I guess,’” Urquhart said, laughing. He agreed to set up a meeting, not sure exactly what to think. “What was interesting was, [Kampanis] said, ‘Put something together about your company, but know that it isn’t really for them, particularly for Trey, because he already knows all the stuff that you do.‘“So that’s what they did: Urquhart put together a presentation of ideas, and when they all got together, he explained to Trey and Matt how Obsidian makes RPGs.

“I went through that very quickly, and [Trey’s] like, ‘I got it. I love this stuff. I don’t like that and this, that, and the other thing,’” Urquhart said. Towards the end of the meeting, Urquhart turned to the two South Park creators and said, “Look: let’s pretend we can do all the RPG stuff. We can handle that. If it doesn’t look like the show, all of this is pointless.” Trey and Matt agreed. “That’s our job,” Urquhart told them. “We need to go and make something that looks like the show.”

So Urquhart got a team together and spent a week putting together a rudimentary prototype. They got the original South Park construction paper from the folks at South Park Digital Studios, and worked to turn it into a polygon-filled interactive experience. “We showed it to [South Park Digital Studios],” Urquhart said. “They said, ‘That’s totally on the right track, once you do a little bit more.’”

Obsidian wasn’t getting paid at this point, but the prospect of a South Park RPG was hard to resist, so Urquhart agreed to keep plugging away at it. They built a prototype set in a house from the show. You played as a generic kid, and you could change your race or clothes by hitting the trigger buttons. If you walked into the living room, you could find Randy Marsh in his underwear, playing Guitar Hero. If you went to the kitchen, you could pick up a spatula, which would then transform into an axe that you could use to smash things. It wasn’t much, but it was the start of a game.

“We took it in to Matt and Trey,” Urquhart said. “And Trey just grabs the controller and he’s like, ‘This feels awesome!’ And Matt runs up to the screen and he goes ‘That’s the construction paper!’ And they were like, ‘Let’s do this.” And that was that.”

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