Having gotten the basic simulation running properly, I turned to a number of lesser tasks. Seeking an overview of the causality net, I prepared a schematic representation. This is it, reduced to 75% size so that it can fit onto a web page:
This might give you an idea of the complexity of this simulation. The player controls the yellow input pages at the top, and the score is presented in the blue pages at the bottom. By examining the structure in this way, a number of design flaws become immediately obvious. For example, look how the Transportation page influences the Quality of Life Score page. The other influence on Quality of Life Score is Economic Growth, which in turn is controlled by Global GDP. Yet Global GDP also controls Transportation. In other words, Transportation simply echoes the value already presented by Economic Growth. Of course, there is one big difference: Transportation awards points for the size of Global GDP, while Economic Growth awards points based on the time derivative of Global GDP. The difference between the two is significant. Moreover, if I rip out Transportation, I might as well rip out Public Transport, Electric Car, and Gasoline Use, all of which, I think, deserve consideration in any environmental simulation. Still, Transportation presents me with an uncomfortable situation.
I have similar problems with Healthy Wetlands, Temperate Forest Land, and Rainforest Land. These are necessary as accumulators for limiting the rates of destruction provided in Acid Rain, Forest Fires, and Rainforest Clearing. These latter three measure the amount of damage, while the former three measure what’s left. This is important because, without the accumulators, it was possible to just keep on raining down environmental destruction on a horse that’s already dead. But it is rather uncomfortable having these things just dangling there like broken threads. I could have them feeding into the Gaia Score in a positive way, but that’s really just doubling the effect of the injurious pages.
I’ll continue studying this schematic; I think that it will help me see the big picture. After all, it *IS* the big picture!