[in response to someone suggesting that the domain rules are 'arbitrary']
They're not arbitrary. They are finely tuned and carefully integrated. The idea that choices can be "arbitrary" is exactly why most domain systems fail. An economy is an interlocking system with emergent properties. GM Fiat cannot address emergent properties and benchmarking leads to absurd results if you don't cross-check the benchmarks against each other, which you can only do if you have a system built to check them with.
It took me 30 seconds to say "1 peasant family yields 12gp per month" and then it took me 10 years to figure out everything that implies about the world. People often do the former and think they've created domain rules, but they almost never do the latter. Then they wonder why their campaign world makes no sense ("I can't afford to field an army based on my population!") and handwave it. They wrongly conclude that handwaving is better because they didn't actually do the hard part of the game design.
I've done the hard work so others don't have to. The ACKS economy has a:
- Demographics of heroism that calculates exactly how many characters of each level there are, based on the availability of activities that let them gain XP, along with their average age, class, etc.
- Bottom-up model. Mixed farming, goat herding, sheep herding, cattle herding, pig farming, olive growing, and wine making are all modeled at the scale of the family, as are lumberjacking, mining, and stone quarrying. I know how much they eat, how much of each good they produce, how much of each good they consume, what their surplus is, etc. All of these are modeled on historical data.
- Top-down model. There's a complete circular flow for the entire continent which calculates the GDP overall, as well as the production quantity of every type of good in the game, and determines how many families are required to satisfy the caloric requirements for different foods, the workforce required for the mines and lumber needed, etc., with every gp entirely accounted for in the circular flow, and with all the input values derived from the bottom-up model.
- Circular Magic model. There's an "economy" of arcane power and divine power based on worship, sacrifice, and reagents. The number of spellcasters of each level is calculated, along with the average amount of research they can do per month, which in turn tells us the inputs required of arcane and divine power and the output of magic items or ritual magic. There's then a depreciation model for loss of magic items of different types each year to anti-magic, destruction, being lost, etc. From this the number of magic items in the world can be calculated based on population growth, and matched to the known wealth of NPCs to determine how many magic items a typical emperor has, etc.
And much more. It just goes on and on. It's over 10 years of work put into it. The ACKS economic system is so good that I was able to use it to predict where Diocletian's prices in his Edict of Prices were *necessarily* wrong. I then researched those specific prices and, voila, I found that other scholars working from historical sales contracts, archeology, etc., had also concluded that those prices were wrong. My model spit out right answers without that data because the model is right. The ACKS model is, without exaggeration, better than anything being used in academia to model ancient economics, to the point that PhDs who have dug into it have suggested I should be publishing academic papers based on it.
So, yah, it's a lot of work. And maybe a lot of people don't care. But it's not arbitrary and it's not something you can emulate with GM fiat or benchmarking.
