From my point of view, there is this difference:
- With the siege, the fiction is already established at the table. And the players can declare actions which draw on that fiction - eg When the next bombardment commences we take advantage of the confusion to enter the city. The players are directly able to build on the established fiction, moving the fiction forward and changing the situation via the play of their PCs.
- With the commercial mystery you describe, the players can't declare actions for their PCs that change the situation until they get the GM to establish more of the fiction at the table. That investigative aspect of the situation you describe is what Hussar has called "following the GM's trail of breacrumbs" - less pejoratively, it's a type of play in which the players' play of their PCs doesn't change the ingame situation - it doesn't introduce new dramatic stakes, or resolve existing conflicts. It simply triggers the GM's narration of additional bits of fiction. Once the players learn about the teleportation circle in the merchants' guildhouse, the dynamic of play becomes the same as the siege. But the period leading up to that reveal is very different.
I fin this a very narrow vision. Who placed whatever the PC's want, that "eyes on the prize" goal, in a city in the first place, then wrapped that city in a desert, then ribboned it up with a siege? Until these parameters were set, there was nothing for the PC's to do. I see a more macro PC Agency potential here -
who set the goal?
In an AP, the goal was likely also set by the GM. Maybe it was set by having the PC's hired to do a job. Perhaps it was set by dangling a plot hook until the players took the bait ("it is rumoured there is powerful magic buied somewhere in the lowest levels of the ruins of the ancient Castle"). Or maybe it was set by mandating a common PC motivation or agenda to start matters of and we went from there ("PC's should be altruistic and have reason to fight the goblin hordes").
It could have been set by the PC's. They could have been placed in the rowboat (a great analogy, Celebrim) and made all the decisions of what they want to do and how they will go about it. But guess what? They need what the GM puts in their path to even do that. In fact, in that rowboat world, the GM has still set the first goal - learn enough about the setting to be able to take some meaningful action.
I think the difference between these two episodes of play is pretty big.
Sure. They highlight different stages in the process. One features the PC's determining the resources that are available to them, what they can do to achieve their goals, or even what those goals could be - like the game(s) where the PC's determined what long term objective they wanted to meet, that the Whatever would advance them towards their goal, and that the Whatever is in the city in the desert. The other features the PC's acting on those resources they have mined from the setting. Few gaming sessions are 100% one or the other.
The siege provides the PC's something new. It wasn't hard to find - there it was. But they still need to set their objectives and implement them. We want to use the siege to our own ends? How do we achieve that? If we want the leaders to take some action, we need to get the opportunity to interact with them, determine their goals and figure out how we can use their goals to further ours. But we need to determine their goals if we are to leverage the siege. Do they want to lay waste to the city and slaughter its leaders? That's a nice matchup for our goal to steal away with an ancient artifact hidden within the city. If our goal is to secure the blessing of the High Priest, that doesn't fit so well with "slaughter the high priest who is one of the leaders". Mabe we can leverage the rescue of the High Priest towards our blessing, or bargain with the besieging force that our aid comes at the price of the High Priest being turned over to us, not slaughtered. Which approach works likely depends on the High Priest's personality as well. If our goal is to secure the principality this city belongs to as our staunch ally, crushing their outost into rubble isn't a great fit.
And here again, we are handicapped by not knowing the goal - the bigger picture - in assessing the siege.
If the besieging force is hell bent to reduce the city to rubble an kill all who stand in their way, there may not even be room for us to interact with the siege. "We scale the walls under cover of bombardment" reduces the siege to a simple "cool image" not really at all different from "we ride our centipede, fremen style, thrugh the desert to the city".
Who said that? @
Hussar seems pretty scathing of Maure Castle (and having had a pretty bad time GMing WG5 when it came out, I tend to agree). I introduced it only as an illustration of how far back in RPGing one can find the idea of introducing an NPC and giving him/her motivations because that serves a metagame purpose, rather than being a derivation of ingame logic.
I see - you inroduced something which merits a scathing rebuke to supot your point. I can't imagine why any of us have difficulty grasping your points when they are presented in such a fashion.
And I can tell you that the phylactery would not have been lying unwarded in a field of buttercups. But nor would it have been protected by a bunch of traps and monsters that bore no connection to the lich or the phylactery other than being procedural obstacles to getting to it. I would have had to come up with a couple of intervening encounters, between players and phylactery, that both reinforced the sense that this is a lich's phylactery we're talking about - it's guarded - but that also spoke to the place of the lich in the fiction and drama of the game - so that they weren't just roadblocks, but engaging situations in their own right.
OK. And you can come up with these in two or thee minutes, I assume, so the game can readily proceed without interruption - Story Now, so nothing else in between. Some GM's can. Some require some prep time. I note ou on't know what they are of the cuff to provide them in our post. I also believe they would be extrapolated from what you (maybe also the layers, maybe not) already know about the lich - otherwise they are unlikely to speak to the place of the lich in the fiction of the game. And, ultimately, I suggest there is no guarantee that the players immediately perceive these links, and don't perceive the next encounter as a roablock. Especially if they are alreay inclined to do so.
Kas has backstory that's known at the table. That's the point of using him, or Vecna, or other "iconic" cosmological story elements. So of course things can't happen that contradict that established backstory.
Esxactly. The layers can make reasonable educated gueses as to what will, or won't, fly.
But that doesn't make the idea of "keeping NPC personalities unfixed, so they can be used to apply pressure", irrelevant. Suppose that the PCs had made the suggestion to join with Vecna, how would Kas respond? I don't know what the answer to that is, but in play I would have it be in some way that keeps the situation moving forward to some sort of dramatic resolution.
I'm guessing, however, that it would not be "Well, maybe getting back to working with Vecna would be fun, you know, for old time's sake. Why I remember when.... Good times, good times..." leading to the Vecna/Kas 'Hells Freeze Over' Reunion Tour. I'm also guessing that your players woul know enough not to suggest such an alliance - their knowledge of Kas assists them in assessing how best to leverage the NPC. Random Roll Mad Mage? Not so much.
In the actual scenario I described upthread, the PCs refused to hand over the niece to Kas, now matter how much he insisted. There are a range of ways that Kas might respond to that. The way I decided was interesting was to use this to reflect the players' playing of their PCs back at them: so Kas said words to the effect of, You can keep the niece if you swear to help me find the grandmother; and I want you to make that oath in whatever terms you made the oath to take the niece back to her uncle, because I want you to keep your promise to me as firmly as you are insisting on keeping your promise about the niece!
Fair enough - Kas' established personality provides no basis for me to wiegh the relative importance of getting the niece versus finding the grandmother, or the opportnit to secure an alliance with the PC's. Now, if the niece had the tols and the will to return Vecna to full power, or could be used to destroy him orever, I would expect Kas to be less accommodating. And, as a PC, I would know his history and have reason to suspect any deal that seems just a bit too good may not be honoured. Whereas, if this were another NPC with a "word is his bond" reputation, that shoul lead me to more trust in his oath - just as Kas is playing upon what he knows worked on the PC's once.
From The Creature from the Black Lagoon to Alien to Friday the 13th, the plot is pretty much the same. Change the spaceship into a campground and you've changed Alien into Friday the 13th. 
