The Economic Loop

Dan Moskowitz

Hello simulation fans! First off, thanks for all your positive responses to our first video. The team here at Maxis is thrilled to be able to share these videos with you. We hope they demonstrate the depth of simulation we’re delivering.

GlassBox is an incredibly powerful simulation engine built by Andrew Willmott, our chief architect at Maxis. He designed it to be elegant, data driven, and to power Maxis-style simulation games - providing a simulation toolkit like none other. As gameplay lead, my job is to take this toolkit and work with the team to create the most alive, tactile, and fun city game ever created - the mother of all city simulation games - SimCity!

In the next few weeks we’re going to be releasing three more videos, each focusing on a few core areas of SimCity and the simulation driving the gameplay. Today’s video is all about the economic loop of the game. What is the relationship between residential, commercial, and industrial buildings in this SimCity? Looking back, each previous version of SimCity had a magic formula for determining the balance of these buildings. Like a lot of the features in this game, we wanted to modernize and refresh the original concept while keeping true to the spirit of the older games, and that was especially true of the economic loop.

Looking at the industrial buildings in the video, they are set to open for business at 6 AM. When the buildings open and realize they don’t have workers, they send out “help wanted” agents that travel down the paths, requesting workers. One thing we skipped over in the video is that there’s actually two different kinds of ‘help wanted’ agents, one that requests people to walk to work and one that requests people to drive to work. The walking requester goes first, and has a shorter distance (a few blocks) than the driving requester. This means that with some foresight and planning you can build fully walkable cities. By playing around with the positioning of industrial/commercial versus residential zoning, you’ll notice commuting patterns unique to your city layout. We’ve found that the organic flow of commuter agents through a city is pretty mesmerizing and a lot fun to play around with. Since you will be drawing the roads and laying out zones, one of the measures of your success is how efficiently the city operates as population increases. For example: Are there enough jobs for residents? Do factories have enough workers? Are stores kept supplied with goods? Of course, you could also just torch the place, that’s fun too.

The other important aspect we’re demonstrating in this video is that simulation rules are tied directly to effects and animation. You can see examples of that when the industrial buildings spew pollution into the air. The rule writing to the air pollution map is literally the same rule triggering the smoke VFX and audio. Same with the factory producing goods, and the conveyor belt animation. We’ve found that by tightly coupling the feedback to the rules, we’re able to convey more information to the player by watching their city run, instead of having to rely as much on 2D user interface.

Check back soon, next time we’ll address how the simulation deals with water, pollution, and sickness.