Prior to founding the independent developer Fullbright, Steve Gaynor was a level designer for Irrational Games best known for his work on BioShock 2's Minerva's Den expansion.

His research for that game, a dark and moody FPS set deep below the sea, included a tour of an actual submarine. So how did he manage to apply that experience to Gone Home, a multi-layered story of personal discovery set in an old Victorian home in the 1990s?

He didn't do it alone. Gaynor said that Gone Home could not have been the critical success that it was without the help of environmental designer Kate Craig and a vintage 1992 Sears catalog.

"One of our big goals in Gone Home," Gaynor said during a presentation at the Game Developers Conference in San Francisco last week, "was to tell a linear story through a non-linear space. ... So, we wanted to make the house and the story feel non-linear, like you were in control of exploring it as the player.

Believe it or not, Gone Home is built like a BioShock level

"That was born out in some of the response that we had to the game," he said, noting that reviews at outlets like IGN and Adventure Gamers praised the title for feeling real and lived-in.

"So success! We did it, right? But... it’s an illusion."

As it turns out, Gone Home shares the same general structure as many levels in the BioShock series. It's a hub and spoke design, intended to gate off certain areas of the map while providing players the illusion of being open and familiar. While that's important for game design reasons, in reality it makes the Greenbriar's home an impossible space, with rooms in weird positions relative to one another and even entire floors floating unsupported. Yet it evokes a kind of reality in the mind of the player nonetheless.

"There’s this concept which I think I first heard about at Irrational Games called 'player RAM,'" Gaynor said. "As you’re playing a game you’re seeing what’s on screen, you’re reacting to what you’re seeing right now, and what has come before, and what you are predicting will come next is kind of passing through your head. But you only have a certain amount of capacity to really hold a high-fidelity image of the overall structure this place is describing.

The player's mind can only hold onto so much at one time

"Because the games that Irrational is best known for take place in these strange, non-real places like Rapture and Columbia. But even when you’re in an objectivist, steampunk, underwater city in 1960, you recognize that you’re coming into a medical pavilion and you’ve entered the reception area, which then leads to a back hallway, which leads to an operating theater. And you say, 'that’s how a doctor’s office works.'"

By not breaking the "chain" of player expectations for how the space is composed in a linear fashion, game designers can essentially brush aside overall issues of structural reality in favor of the overall atmosphere and pacing of the experience. They can make the unreal feel real by simply meeting players expectation of what logically comes next, and Fullbright used that strategy to great effect in Gone Home.

But, Gaynor said, it was still his job to make the player "feel like you were in the place this space is describing." That required a kind of subtlety in Gone Home's game environments, and that's where Craig's work became invaluable.

Once the team settled on a Victorian home, Craig went to primary texts at her local library to create a body of historical knowledge from which to base the game environments in. Then, she layered the environment with decade after decade of period furniture and ephemera, giving each wing and each room in the Greenbriar home its own story to tell.

In the fiction of the game, Gone Home takes place in 1995. So to make the top-most layer of the game environments, Craig ordered a vintage 1992 Sears catalog from eBay. The well-loved book has traveled with her ever since.

"It looks like garbage," Craig said as she rifled through the pages wistfully on stage before the packed crowd in San Francisco. "I’ve literally taken this all around the world with me at this point. … So it’s about to fall apart."

But, she said, it wasn't a simple matter of copy-pasting furniture and light fixtures into the game. It required a kind of restraint.

"If you start pushing too hard on the nineties nostalgia, it can seem like parody," Craig said, showing a section of the catalog featuring a carpeted bathroom. "There’s carpet on the toilet tank, too. ... But despite being of the period, it was just entirely too much. So we did include some items almost exactly ... but some objects were just subtly tweaked.

"We were such a small team there wasn't really an art director," Craig said, "but there was Steve. Every time I had a question or a concern I would go to him and pitch him something and he would be like, 'Uglier.'"

"We wanted the white wicker bedroom set," Gaynor said, citing an example. "But the white wicker bedroom set in the catalog is not quite ugly enough."

"Right," Craig said, doing her best Gaynor impression. "'This is garbage,' he finally said. 'I love it.'"