I must take great care not to create a mere series of puzzles; the meat of this storyworld must lie in the interaction. Specifically, Mordred must challenge Arthur in a way that constitutes not a puzzle but an interactive conflict. Here's an example of the problem: recall the latrine substory in the earlier Le Morte D'Arthur. In this substory, Mordred confronts Arthur at the latrine, prominently displaying his manifestly larger penis. Arthur must then respond. This is a puzzle; it is one-dimensional. There's nothing wrong with a few of these -- indeed this one is so cute that I have to include it in the new version. But such puzzles must not be the core of the design, for they are not interactive.
To make the transition from puzzle to interactivity, Arthur's responses to Mordred's provocations must be highly context-sensitive. To put it another way, each of Arthur's options must in certain situations be the best option. If I can ever pinpoint any particular option as always best or always worst, then I have failed to design the options properly.
I am tempted to leap to the assertion that this requirement mandates trade-offs in all decisions. That is, each option must trade off two desirable factors (or two undesirable factors) against each other. Central to this is the notion of "rational uncertainty" as opposed to "arbitrary uncertainty". The latter is what we find in puzzles (example of arbitrary uncertainty: the fish and the vending machine in Hitchhiker's Guide to the Galaxy). What I need is uncertainty that yields no resolution.
Here is a more rational, less arbitrary uncertainty: Arthur's in a battle and things are going badly. He could order a retreat, but this would leave one of his supporters exposed and liable to destruction. Or he could stand firm for long enough for the vulnerable supporter to extricate himself and participate in an orderly retreat -- but this option might lead to a much larger defeat of the entire army. Does Arthur cut his losses and abandon the supporter, or does he hang in there and risk the whole army? This is a more rational uncertainty, but it remains somewhat puzzle-like in that there is a correct answer. Of course, that correct answer depends on the circumstances of the battle, and so satisfies my earlier criterion requiring any option to be the best option under different circumstances.
But here's an even more rational uncertainty: how will people react to a given act? Suppose, for example, that Mordred, in front of a large group, derisively calls Arthur a wimp. Suppose further that one of Arthur's options is to punch Mordred in the face. Would such an act impress some people as manly self-assertion, or disgust them as unbecoming a king? That's a permanent uncertainty -- different people will act in different ways and Arthur will never know the truth.
All this certainly implies a strong feedback mechanism for Arthur. That is, people should be coming to him frequently, voicing their opinions on his past actions and future options. This is the only way that Arthur will find out about their personalities and preferences.
OK, that implies a simple structure for each subnet: establish context, present dilemma, collect Arthur's choice, present character opinions. The storyworld as a whole boils down to one damn dilemma after another.