It may be that I have a stubborn streak. It may be my personal interpretation of science and the scientific method when I was young and imagined myself growing into Walter Reed or Charles Darwin. Perhaps it is because I just want things to be harder than they have to be.
Nevertheless . . .
If we have it in our minds that we are going to build a structure that our game worlds will obey, we must first understand that the structure we design must be more important than our feelings about it. For the structure to serve its purpose - that is, to provide a framework that the players will be able to predict as well as ourselves, we absolutely CANNOT change that framework, EVER, to suit a given circumstance or situation. If we change any single entity or element of that structure, we must understand that the change must be to every other similar entity. If we make specific exceptions for specific entities, we don't have a structure. We have a collapsed pile of shit.
For example, let us say that the players move into an area where hobgoblins dwell. After a session or two, the players learn that this is a hobgoblin kingdom, with hobgoblin cities and hobgoblin overlords - where everything non-hobgoblin is treated with disdain and with a will to cause the players certain death. This can be good and scary, particularly as the players now find themselves having blundered sixty or eighty miles into hobgoblin territory. We can now have a very powerful campaign where the players must rely upon their own strength and sense of direction to be safe again . . . so long as the hobgoblins live up to that expectation!
But if the DM decides to inject a hobgoblin family that shows kindness and compassion for the players, helping them get out of the country, whoops. Probably, the DM figures, "Well, not all hobgoblins have to obey the norm. And the players are safe." Yes, they are. No doubt, the DM feels very clever, putting in hobgoblins that aren't sadistic and cruel, blowing the stereotype. Too bad, the players did not have to rely on their own resources. The DM helped them. Making the campaign a dud. Hobgoblins? Meh. Not as nasty as their PR.
DMs everywhere wonder why campaign after campaign crashes and burns into player jokes, mockery, cheap bravado and ennui. They do, because the DM's word is not the DM's bond - not only in the sense of the presentation from night to night, but in the world itself. Because every time some structure in that world challenges the DM's preconceptions about what society ought to be or how people in a society ought to act, the DM immediately begins looking at the game from the perspective of someone socialized to interact in the present day, in a heterogeneous world where people aren't allowed to behave inflexibly or intolerantly.
Unfortunately for such DMs, much of the drama that makes tension is based upon characters, social systems, societies, cultures or philosophies that are incredibly inflexible.
Consider, for example, any horror movie of your choice. Let's say, The Hills Have Eyes, that more or less describes the situation I've just described above. The structure here is that the psychotic cannibals of this particular desert are ready to kill a party (family) that has just blundered into their territory. There is no out except survival. No remorse on the part of the killers, no rescuers, no survival except what the party attempts, no guarantees of survival, etcetera. Plus lots and lots of tension. So much tension that the DM (or director) gets uncomfortable with the situation - but unlike a DM, Wes Craven just doesn't give a shit. He doesn't let his audience off the hook because that is the fucking point.
Most DMs do get uncomfortable with the structure, particularly as they watch their players shift from apparently comfortable fun times to oh my fucking gawd we're all going to die. At that point, most DMs piss all over their own structure, help the players (fudging dice, injecting surprise allies, padding the treasure give) and destroy the tension.
When I say that I want a tech system that will limit an area's ability to provide resources (or contrariwise, with the higher techs, provide scary and aggressive authority figures with the power necessary to make life hard for the players), I mean that I want a tension-building structure that the players will have to accept and build their way past if they want to continue to accumulate treasure and power. I'm not looking for a cutesy interesting fluff formula for painting the background. I want a firm, stable and absolutely inviolable structure that says "NO, the tech level is this. Live with it!"
This structure ideal cannot work if I am willing to circumvent it. Damn, I don't know how clearly that has to be said. I cannot - CANNOT - break my own structure. When I do, I've compromised my players expectations, I've compromised their faith in me and my world, I've compromised the experience they could have had if I hadn't let myself off the proverbial hook. I have to strain myself, always, to go that much further in adjusting the structure within the boundaries I've created. Otherwise, I need to trash the structure and replace it with one I will obey! Otherwise, I'm only compromising my principles, those based on my world living up to the game as it deserves to be played.
In the structure, sometimes, adjustments do have to be made. Something is definitely going to have to be decided about the six market cities I now have in tech 5 regions. I'll talk about that soon. Those adjustments, however, cannot be decided on a whim. The determination for how the structure is changed must be universal to all situations and they must not compromise the fundamental purpose of the technology level design - that is, to encourage a given behaviour in me and behaviour in my players.
Until the reader understands the principles of behavioural design, forget ever making anything that will invoke a useful, practical response in a user.