SimCity modder says game doesn't appear to offload significant calculations

Shortly after the botched launch of SimCity, Maxis general manager Lucy Bradshaw told Polygon that one of the reasons the game doesn't support an offline mode was because a "significant amount of the calculations" required by the game were being done by the game's servers.

"With the way that the game works, we offload a significant amount of the calculations to our servers so that the computations are off the local PCs and are moved into the cloud," she told Polygon.

But a duo of programmers and database engineers who have been analyzing the communication between local games and SimCity servers say that according to their research that simply isn't true. EA has not responded to requests seeking comment on this issue.

"It's not possible that EA servers are 'offloading' calculations (simulations) for your city, which it works out, and then sends to your client," Azzer Cronin told Polygon. "Not at all. Your client simulates your city, and your client simulates all of the 'fire trucks from another city' type stuff too. Your client does that all. EA servers do not do any processing that your client is incapable of because our 'computers aren't powerful enough.' EA servers do no complex calculations 'on our behalf' that it then passes the results back to us and that our clients need to run the game."

Cronin and his friend Alex "Weeble" House made a name for themselves shortly after the game's launch when the posted a video showing that at least some form of offline play was possible for SimCity.

According to the Cronin's initial posts on Reddit, while the game can be played indefinitely without connecting online, it is not possible to save the game without reconnecting to SimCity servers and cross-city play is also impossible.

Since then, Cronin and House have been tinkering with the online-only game's inner workings, trying to figure out what is being done locally on a computer running the game, and what is being handled by the servers.

While speaking with Polygon, Cronin was clear that he can't determine everything that the servers are doing for the game, only the data that is being sent back and forth between server and a local computer running the game.

"I can tell you what your (computer) is doing, and thus what the server isn't doing," he said. "But I can't tell you what the server does by itself (eg. cheat checking, gathering global statistics on all cities, things like that), I can only take some decent educated guesses there."

For instance, Cronin says he couldn't tell us if the servers are looking for cheaters by calculating if a city is growing abnormally large in a short period of time.

Instead, Cronin focused on figuring out what data is being sent back and forth between the server and local game. He said he wrote a short script that logs every request for data SimCity makes to the EA servers and the data it receives back and every bit of data it sends to those servers.

He then used that information to determine exactly what a person's computer is calculating and extrapolated what he believes the EA servers are calculating.

According to his information, Cronin believes that a person's computer is doing all of the simulation for the city as well as handling the simulation of things received from other cities in a region, like spare water or an extra fire truck.

According to his information, Cronin believes that a person's computer is doing all of the simulation for the city.

What's that leave for the servers to calculate?

Cronin says he believes the servers are essentially functioning as go-betweens, handing off a raw list of what's available from other cities in a region, like water, power and spare fire trucks.

Cronin says the way the game works currently is that the moment a person stops playing a city, that city essentially becomes frozen in time. A city's resources are only depleted and a city is only affected when it is actively being controlled by the owner of that city, he said.

An offline mode, Cronin says, could be created by allowing a person to maintain all of the cities in one region, freezing the ones not currently being controlled. The computer could track all of the data locally if all of the cities in a region were controlled by the same player on the same computer, allowing the game to cut out the need to pass information to a server and then back to the local computer, Cronin said.

We've reached out to Electronic Arts repeatedly over the past week for confirmation on what calculations are being performed by servers in SimCity, and while representatives have sent us links to blog posts and even some short interviews, which we ran, that question remains unanswered.

Most recently, Bradshaw wrote a blog post further discussing why the game isn't an offline game. In that post she didn't reference the need for sever-side calculations directly saying instead that Maxis' "innovative use of servers to move aspects of the simulation into the cloud" is implemented in several ways. That includes, she wrote, including the handling of simulation state of regions, exchanging gifts between players, keeping track of social world features, modeling dynamic supply and demand and verifying the legitimacy of players' saved cities.

"So, could we have built a subset offline mode?" Bradshaw wrote. "Yes. But we rejected that idea because it didn't fit with our vision."

SimCity's launch was initially plagued by massive server issues that saw gamers unable to reliably play the game during its launch week. It remains unclear why the servers failed to keep up with demand. Earlier this week, Electronic Arts detailed its plans to give a free game to SimCity owners to make up for the launch. It also announced that the game sold 1.1 million copies in its first two weeks.

The day before publishing this story we emailed EA representatives a summary of Cronin's findings and asked for both a reaction and a statement as to whether or not the information he uncovered was correct. Their last response to us, sent yesterday, was to thank us for the opportunity to reply and say that they would be in touch in the event they want to respond. As of publishing time, we have not heard back.

Update: Rock Paper Shotgun's John Walker spoke with Cronin last week on the same topic, you can check out his interview here.