This is a step between what I have and what I want.

What I want is a mini-game that works similarly to d20 combat, and yet is open-ended enough to add or remove ‘creatures’ from combat — to basically do what the 4e Skill Challenge was intended to do.

To that end, I created six “investigation” scores:
Question
Postulate
Observe
Explore
Analyze
Research

Let’s pretend for a moment that you generate these scores the same way you would in D&D — 3d6, right down the line — and that you assign modifiers in a similar fashion. An 18 awards you a +4 bonus, and an 8 carries a -1 penalty.

Those of you familiar with the Scientific Method may note some parallels — question, hypothesis, prediction, experiment, and analysis.

I’ve combined hypothesis and prediction into a single ‘postulate,’ separated experiment into ‘observe’ and ‘explore,’ and added ‘research.’

What I hope to do next is create an “unfolding” system — supplanting the rigid structure of a Skill Challenge — so that an investigation has only a pre-defined beginning and a central Mystery, which then is either fulfilled or escalates.

I think I’ll review Genius: the Transgression to see if there’s some material to be mined from how Wonders are created and interact with the game environment — one idea incorporates “variables” as a means of determining difficulty.

An investigation has a number of Variables which define its difficulty.

As the characters probe for answers, they either Prove something — gain some measure of success — or experience a Crisis. In a Crisis, the characters stand to lose and must complete an associated mini-game (for now just picture this as a saving throw action or whatever) or the investigation fails catastrophically.

Once the characters have nailed down each one of the Variables, they have a Hypothesis which they must then check against the Mystery.

If the Hypothesis fails, the investigation escalates somehow. This probably involves additional Variables, but I don’t know yet — I haven’t drafted the procedures yet. We’ll see then if this system is as flexible as I hope it is.