I don't think I feel the force of the contrast you're drawing between a killing and a possession as events which might be attended by mystery. But I assume you regard the cult's weapons as more closely resembling the latter than the former.Your second example is closest to what I mean, but it feels a bit too..."weakly" mysterious, if that makes sense? The events are well in the past, and there's a lot of leeway for how things had played out, which makes the revelation of the black arrows feel like a fun surprise rather than a "whatever you come to believe was right all along." The issue may be (I'm not sure) that the murder mystery feels like a relatively "closed" event (e.g., every true murder victim has to have died in one and only one way, there has to have been at least one killer, there was at least one weapon or object that killed her, etc.), whereas with this possession, it feels like legitimate new understanding could arise at any time as we learn more about what it all means and what happened around that time. You can't really understand a murder as something other than a murder, but a "possession" could have many meanings and become far more nuanced as you learn more of the how and why. (Admittedly, some murders have context that changes things...but all it can really do is either reveal that what you thought was the true cause of death wasn't or that who you thought actually did the deed did not.)
I guess what I'm saying is, "why did my brother get possessed?" is a fundamentally different kind of mystery from a murder, theft, fraud, etc. It is a question about purpose and justification, rather than about facts-of-the-matter per se. Answering that kind of question feels like enriching the play experience, establishing new background, redirecting the trajectory, and I'm more than cool with my players doing those things. It does not feel like "once we see enough clues, we will then declare what the events were and that will be what the past always was." Note that this does differ from proper illusionism because the players can be in author stance with it. But it reflects the same..."history is clay in our hands" perspective. That causality itself bends to whatever makes sense in the fiction, since chronologically later events (examining things and developing beliefs about them) causes past events to be a certain way and no other.
I don't quite follow this. Waking up from unconsciousness in a manor seems like it would fall within a pretty typical range of consequences for a failed check in a mystery/horror context.The third thing I honestly don't know how to parse. It sounds like use of force to me, and to a problematic degree, at least for the part where they wake up in the manor.
I don't really follow this either. Suppose many lines of inquiry and player suppositions suggest that X is the perpetrator. Couldn't one consequence of failure, at the resolution point, be that really it was Y all along?The characters don't appear to have the freedom to be wrong (whether in whole or in part), because the threads will be drawn together no matter what, it just might be more complicated than expected.
Where is this coming from? A mystery scenario can resolve without the mystery being solved.If the mystery is fore-ordained to be solved
For instance, in the first Cthulhu Dark scenario I GMed the scenario resolved - the PCs drove the merchant ship with a mysterious cargo in its hold onto the rocks - but they never learned what the cargo was. Nor do I think it was ever established who exactly committed arson on the houses of two of the PCs.
Especially in Cthulu-esque play, there can be resolution without answers.