When I started measuring out our local grocery store, which I don't think of as being that big, I was blown away by how much more space was parking lot rather than actual store. That was kind of a problem, because we were originally just going to model real cities, but we quickly realized there were way too many parking lots in the real world and that our game was going to be really boring if it was proportional in terms of parking lots.

Stone Librande, Lead Designer of SimCity (2013)

Full Inteview here:
https://www.theatlantic.com/technology/archive/2013/05/the-philosophy-of-simcity-an-interview-with-the-games-lead-designer/275724/

Some interesting parts:

Nicola Twilley: I thought I'd start by asking what sorts of sources you used to get ideas for SimCity, whether it be reading books, interviewing urban experts, or visiting different cities?

Stone Librande: From working on SimCity games in the past, we already have a library here with a lot of city planning books. Those were really good as a reference, but I found, personally, that the thing I was most attracted to was using Google Earth and Google Street View to go anywhere in the world and look down on real cities. I found it to be an extremely powerful way to understand the differences between cities and small towns in different regions.

Google has a tool in there that you can use to measure out how big things are. When I first started out, I used that a lot to investigate different cities. I'd bring up San Francisco and measure the parks and the streets, and then I'd go to my home town and measure it, to figure out how it differed and so on. My inspiration wasn't really drawn from urban planning books; it was more from deconstructing the existing world.

Then I also really got into Netflix streaming documentaries. There is just so much good stuff there, and Netflix is good at suggesting things. That opened up a whole series of documentaries that I would watch almost every night after dinner. There were videos on water problems, oil problems, the food industry, manufacturing, sewage systems, and on and on -- all sorts of things. Those covered a lot of different territory and were really enlightening to me.

Geoff Manaugh: While you were making those measurements of different real-world cities, did you discover any surprising patterns or spatial relationships?

Librande: Yes, definitely. I think the biggest one was the parking lots. When I started measuring out our local grocery store, which I don't think of as being that big, I was blown away by how much more space was parking lot rather than actual store. That was kind of a problem, because we were originally just going to model real cities, but we quickly realized there were way too many parking lots in the real world and that our game was going to be really boring if it was proportional in terms of parking lots.

Manaugh: I'm curious how you dealt with previous versions of SimCity, and whether there was any anxiety about following that legacy or changing things. What are the major innovations or changes in this version of the game, and what kinds of things did you think were too iconic to get rid of?

Librande: First of all, when we started the project, and there were just a few people on the team, we all agreed that we didn't want this game to be called SimCity 5. We just wanted to call it SimCity, because if we had a 5 on the box, everybody would think it had to be SimCity 4 with more stuff thrown in. That had the potential to be quite alienating, because SimCity 4 was already too complicated for a lot of people. That was the feedback we had gotten.

Once we made that title decision, it was very liberating -- we felt like, "OK, now we can reimagine what the brand might be and how cities are built, almost from scratch."

Technically, the big difference is the "GlassBox" engine that we have, in which all the agents promote a bottom-up simulation. All the previous SimCity games were literally built on spreadsheets where you would type a number into a grid cell, and then it propagated out into adjacent grid cells, and the whole city was a formula.

SimCity 4 was literally prototyped in Excel. There were no graphics -- it was just a bunch of numbers -- but you could type a code that represented a particular type of building and the formulae built into the spreadsheet would then decide how much power it had and how many people would work there. It just statically calculated the city as if it were a bunch of snapshots.

Twilley: Actually, one of the questions we wanted to ask was about time in the game. I found it quite intriguing that there are different speeds that you can choose to play at, but then there's also a distinct sense of the phases of building a city and how many days and nights have to pass for certain changes to occur. Did you do any research into how fast cities change and even how the pace of city life is different in different places?

Librande: We found an amazing article about walking speeds in different cities. That was something I found really interesting. In cities like New York, people walk faster, and in medium-sized or small towns, they walk a lot slower. At one point, we had Sims walking faster as the city gets bigger, but we didn't take it that far in the final version.