I am not talking about should, I'm talking about could. Things such as 'this thing contains a ghost and tries to souldrain you' are pretty damn easy to place in various differnt places without it feeling forced at all. Furthermore, there is a continuum from 'totally made up on spot,' 'made up on spot but influenced by some vague musings the GM had before' to 'totally preplanned.'
I'm now not sure what you're aiming toward. "Hold on lightly" means don't get locked into an idea such that you push it on the game. If you have an idea and later it fits, cool, but the issue here isn't Illusionism -- you're not planning to present an outcome regardless of choice. It's not illusionism, even if you have some ideas and they work out. Generally, though, I don't bother much with thinking ahead -- the odds it will be useful given how the game plays if very low.
If your intent is to go "aha, could possibly happen in this game and so it is no different from a game where it happens all the time," well, good luck with that -- you can imagine that it might, and a GM is not playing according to the rules of the game, and that it happened, but I don't think this is remotely the same as the game that does everything short of directing you to use Illusionism.
Right. So you found a cursed manor in the setting lore and decided to send the PCs there. This is how Curse of Strahd works too. The players decided to seek information about a thing, but you decided where they have to go to get the thing.
I think you missed a few steps and zeroed in on the least important. The players were seeking the cult for their own reasons, and told me that they wanted to do this. The players used their contact in Six Towers, setting up play to be in this area. Sure, at this point, I had a scene to set, but we're already dealing with creepy cult and a haunted district and the fact that the source sought was one that traded in ghosts, so -- it's not like I just arbitrarily picked a haunted house or wrote down in my notes "the players must go to the haunted house to retrieve a macguffin." The choice of a haunted house was pretty far down the chain of player choices, and it directly flowed from those choices in theme.
And I am sure there are countless differnt framings that could have fit those results. This was one of them and you chose it. And that will affect what the players do.
Another trivial statement. In fact, this has been used to argue against some of your earlier claims that things should play out in a certain way. It's a tad ironic to see it show up when you find it convenient.
A lot of this could have indeed be planned in advance. And even when it wasn't, you made a lot of choices that massively impacted the direction of the game. Not that this is bad thing at all, but I feel you're downplaying the amount of influence the GM has here.
No, it couldn't. I'm trying to make this clear. The sessions started with a quick review of what's recently happened, and then it's on the players to pick a score. I, as GM, get no say in what they decide to do. I have to go with what they want -- if they want a score to make some coin, well, that's what's what. We do some free-play, where they get information -- this isn't a question, it's a definite, they get information on whatever they want to do next. There's maybe some fortune rolls, maybe an action check, but it's pretty straighforward -- I'm not allowed to say "no" or block, by the rules of the game. So, here, again, I have very little control to determine what's the score is even going to be about! And, then, once that's done and we're starting the score, the players pick their plan, which are different thematically, and then their detail, and then we have a quick negotiation on modifiers to the engagement roll, and that sets the position for the opening scene of the score. Again, following the details, I skip to the action and narrate a successful entry according to their plan and detail and start with the first obstacle they have to overcome. This is the first time I, as GM, really have any authoritative input, and it's tightly constrained by all of the above. I challenge you to plan for this kind of thing -- it's not possible.
But the Gm decides the position, which is based on the fiction which is based on their framing so...
It's also based on the action. If I narrate an open courtyard, and the player wants to run across it stealthily, I can say that, sure, that sounds Risky (default unless good reason exists to change it), but can say that the courtyard is big enough that the Effect will be lesser -- you'll get halfway across and we'll see what happens. The players can challenge this, and say, "wait, you didn't say it was a large courtyard, I thought it was smaller than that," and I should eat this because they're right, I didn't. I don't get to make things up at the point of setting the position and effect -- it has to already be there to do so. And, again, the rules are that actions are Risky unless there's a good reason and effect is Normal unless there's a good reason. Good reasons have to be apparent to everyone at the table. My usual statement when setting Desperate is, "whoa, that sounds pretty desperate/hardcore/dangerous, I think that sounds Desperate, what do you think?" Players have almost always agreed with me, because they know what's up and know I'm dealing fairly.
This certainly may influence my views.
But you knew the character's motivation, so it is even easier. You also know your players and if playing live can read their reactions. I am not saying that you were intentionally guiding them, but that could easily be done.
See, here's the thing, I don't pay attention to that much at all! It's the player's job to bring the things they care about into the game, not mine as GM. I shouldn't block, and should offer opportunities, and it's okay if I pluck something out, but really it's not my job to do this. If they want to bring something up, then it works exactly like my example works -- the player makes it a thing. I mean, I get that you really want your point to stick, for some reason, I guess so you can say this is the same as D&D, but we're discussing some kind dickish things to do to friends or fellow hobbyists, so maybe can you tone down the half-accusations that I want to manipulate things? This is shading heavily into bad-faith play, and any argument based on bad-faith play is the problem of bad-faith, not the system or approach.
Not necessarily so. You can offload a lot of decision points to mechanics and randomisers, so no one has agency over them. I think Blades does that quite a bit. And with these sort of mechanics I have to question how meaningful the decisions ultimately are. There has been a lot of talk about Czege principle (usually not by me.) But if I want to know whether an item is a magical and my act of investigating it makes it so that it is, how is that not violation of that? Would certainly seem rather unsatisfying to me.
Okay, sure, let's look at this. Let's say that we have a situation where the players have declared an action. We can let the GM decide, in which case the GM has a lot of agency and the players not much, because the GM has the say and the players don't. We can imagine a situation where the mechanics do all of the deciding -- they must be invoked and live by. This is the boardgame approach, and neither the GM nor the players have much of a say. Then we can look at something like Blades, where both the player and the GM has a say on different aspects, and we just let the mechanics decide who has final say on this issue. Evaluating for player side agency, they have very little with GM decides (mostly just the ability to pose the action); they have very little in the mechanics always system (again, just the ability to pose the action); but they have more agency that either of these in the system where they get a say in how the mechanics work and the mechanic might give them the final say! They don't have this in any of the other toy examples.
As for Czege Principle, your example is a violation. Play in Blades doesn't do this. If it's not important, it's not a challenge, it just get's yessed. If it is important, it gets challenged -- the player states an action to determine if this sword is magical. No one knows if it is or not, we're going to play to find out. The player's intent and action is determined, the GM sets Position and Effect, and we make a check to see if the player is right -- it is magical how they hoped, or if it is but there's a problem, or if the GM gets to level a consequence. Here, the player did set the challenge, but not the resolution -- they are not both the author of the conflict and it's resolution, the mechanics and GM step in to assist with the resolution. Perhaps the player wins, but that's not a violation because the player didn't just narrate the resolution, it was the result of a test. There was drama involved.