Simulating a Planet's Economy from Inception
The prototype economic simulation was seeded with a 'pre-rolled' population and wealth, and aimed to create some kind of stable consistency up or down in growth, given a decent start. Each planet began with generous conditions - say 3 billion population and 60 billion credits of wealth.
The real aim for the game however is to simulate each planet's evolution from first inception, such as landing just 100 colonists and giving them a measly 1,000,000 credits to eventually (hopefully) build an entire civilisation from.
Under the prototype code, most planets died out very quickly. Tiny destabilising factors that reduced population would quickly reduce the population to 0 when only starting with 100. The large costs associated with building and maintaining production infrastructure such as mines and refineries were overwhelming to begin with and easily overpowered small populations.
To cope with this I've added population scaling factors, more stabilising behaviours and have simplified the simulation so that it can be more easily balanced. To achieve this the simulation now focuses on two main elements - desirability and wealth.
Population Growth is now primarily determined by a 'desirability' rating for the planet. Desirability is made up from tax incentives, per-capita wealth and overcrowding.
As desirability of anything is somewhat ephemeral at best, I've tied the planet's stability rating to the determination of desirability, adding a randomising factor driving population. As those who write Genetic Algorithms know, a little bit of randomness can help dislodge a population from being stuck in a local peak and help drive them towards finding the global maximum.
Wealth is now an accumulating factor, calculated each year from GDP, Production capacity, Labour Force (population), Infrastructure Maintenance Costs and Tax revenue.
This is meant to be a complex system with feedback cycles. So wealth drives desirability which in turn affects population which subsequently affects the labour force and thus production capacity and wealth.
Here are the results of the next iteration in planetary economics. Each of these planets start with 100 colonists and 1,000,000 credits. They still begin with production infrastructure, the plan is for infrastructure to be built on-demand by government policies as the simulation evolves in a future iteration. These planets are now simulated for 1000 years from inception.
Most of them take a long while before the population (blue line, top image) finally achieves real growth. But each planet after 1000 years has achieved some manner of stable population and wealth. Another point of note is the desirability factors in the bottom graphs. The less stable the planet's government is, the more noise in the desirability rating. And when a planet grows too much, the negative desirability due to overcrowding (yellow line) can be seen to really dampen down any new immigration.