I understand that a simulation need not conform only to the rules of our own reality. Rather, as I have understood the term, simulation requires that it have rules--whatever those rules are--and those rules are ultimately never violated.
<snip>
That is where simulation gets is association with "realism," or rather groundedness, to use my not-quite-identical term. A game (or any medium) that fails to be sufficiently grounded, either by failing to resemble the audience's perception of the real world ("realism") or failing to explain itself sufficiently so we develop an intuitive awareness of its rules, will fail to be a simulation. Even if it is otherwise very good at establishing the chain of material causation (or "more detailed," as you put it), a lack of groundedness is a fatal flaw from a simulation standpoint, and "like the real world" is the low-hanging-fruit of writing grounded things.
What examples of RPGs do you have in mind?
I think the notion of simulation that
@Hussar has put forward is fairly straightforward, has a reasonably stable pattern of usage over time in relation to RPGs (
around 10 years ago on these boards it was often called "process simulation"; Ron Edwards,
around 20 years ago, called it "purist-for-system simulation"). The basic idea is that when the mechanics of the system - action resolution mechanics, and perhaps also PC build mechanics, and perhaps even content-generation mechanics like encounter checks or world-building tools - are used to create new fiction, they correlate to, and in some fashion model, the in-setting causal processes that (within the fiction) are the causes of the new stuff.
In RQ we see this in the combat system and the PC advancement system (ie learn by doing). In Classic Traveller we can see this not only in the PC build system (it models in-fiction lifepaths) but in the encounter system, and even the framework for rolling up alien animal species. (The contrast here with D&Disms like hit points, or very traditional wandering monster checks, is clear.)
There is no particular need for
inviolate rules as part of the fiction - just that the mechanics, when used, map out the in-fiction causation to which they correlate. Because the in-fiction causation is not going to be spelled out in the sort of detail that an engineer might typically hope for, it will often trade on the players' common sense about things (eg we see this in Traveller's animal gen rules: thinner atmospheres have fewer, and lighter, fliers). Maybe that's what you mean by "groundedness"? But it doesn't particularly depend on inviolate rules. RQ's learning-by-doing, for instance, is based on random rolls not inviolate rules, but it still achieves the simulationist RPGer goal of having the character's development, in in-fiction causal terms, being modelled by the rules for PC build. Contrast the complaints one sometimes sees, that D&D permits the grafting on of mutliclass levels with no in-fiction explanation for where that character development came from.