Ovinomancer
No flips for you!
I get what you're aiming at here, I just question why you're doing so, or maybe why you're coming at the issue so obliquely. 5e is not a system that can provide your preferred experience, although some pieces of it do well. Now that I see what you were aiming at with your example I think there's some daylight between being able to "control what the PC thinks and does" and your example. Fundamentally, this is on whether the thoughts and deeds of the PC are able to determine game fiction outside the character. In 5e, this is (baseline) untrue. The player is free to declare they think they know the guard and act accordingly, but the GM has no obligation to agree about the fictional state of the guard.I'm happy to accept that it's malformed in the context of 5e D&D. But I don't see how that conclusion can be reached without giving some account of who has what authority over which bits of the the fiction. And saying that the player has authority over what his/her PC does, thinks and feels isn't going to do the job - because Hey, that's my old friend Frances - I ask her to let us through the gate! is an example of the player deciding what his/her PC does, thinks and feels.
Nor do I think it's enough of an answer to say that players have no authority over any aspect of the fiction except action declaration and associated bodily movements by their PCs. Page 33 of the Basic PDF says that "Characters are defined by much more than their race and class. They’re individuals with their own stories, interests, connections, and capabilities beyond those that class and race define." There are sidebar examples throughout the PDF of two characters (Tika and Artemis) who are distinguiished - as those sidebars emphasise - on the basis of non-mechanical details of the fiction. That seems an invitation to players to make up similar stuff for their PCs. Deciding on Ideals and Bonds seems also to invite the player to make up people and places that their PCs care about and are connected to.
In the context of this thread, I think that [MENTION=22779]Hussar[/MENTION] has made it fairly clear that one reason he doesn't like the "goal and approach" method of action resolution is that it privileges the GM's conception of key aspects of the ficiton over possibly differing conceptions held by the players. Others obviously disagree, taking the view that exercising such authority is the prerogative of the GM. But upthread, [MENTION=6801328]Elfcrusher[/MENTION] gave an example of a player authoring shared fiction invovling the stories told to a young PC by trial elders. I don't think many posters regarded this as a usurpation of the GM's authority. The general response to my post seems to be that the player deciding that the gate guard is her/his PC's childhood friend Frances is a usurpation of the GM's authority. But in some other recent threads I've seen criticisms of a GM narrating failure as some sort of oversight or carelessness on the part of the PC as a usurpation by the GM of the player's authority over deciding what his/her PC does, thinks and feels. Likewise there's a widespread view that it would be usurpation for a GM to decide that a PC didn't do what the player has said s/he does, because the GM thinks it is inconsistent with the PC's stats.
These boundaries aren't crystal clear to me, and I'm a pretty experienced RPGer. I don't find them clearly articulated in the 5e Basic PDF. I'm sure I could get by in [MENTION=97077]iserith[/MENTION]'s game playing a "man with no name"-type character, but nothing in these threads has given me any indication of how I might go about playing a character who is genuinely embedded in the social context of the gameworld - even though the Tika/Artemis sidebars, and the more general tenor of chapter 4 of the Basic PDF, all give me the impression that the game is focused on such embedded individuals.
Goal and approach is - as I understand it - all about engaging the fiction so as to mitigate the difficulty of the challenge (or, perhaps, aggravating it so as to earn Inspiration).
I'm not disputing that a boundary can be articulated which explains why I pull out my crowbar and use it to lever the door open is OK but There's my old friend Frances, one of the guards now - I ask her to let us through is not. I'm just saying that I haven't seen it articulated yet. And although you emphasise not carrying baggage from one game to the next, at the moment the only grasp I am getting on the boundary is by ignoring chapter 4 of the Basic PDF and instead remembering how most traditional RPGs allocated GM/player authority over the ficiton from the 70s through most of the 90s.
This last is the important distinction. Being able to determine what your PC does and thinks doesn't extend to establishing new functional avenues to current challenges. Let's contrast your guard example with the troll example. In the troll example, the player establishes the PC's uncle told the PC about trolls' weakness to fire. This is to "justify* doing so within the fiction. But, the ability to use fire on the troll isn't causally tied to this bit of fiction. This fiction does not enable previously unavailable actions.
Your guard example, though, does establish new actions that weren't available before the introduction. The player is now trying to establish fiction in the current gameworld to enable new casual paths to overcome the immediate obstacle. This isn't allowed in 5e -- it's outside the player's narrative authority because the player is now describing elements of the scene alongside their actions.
A 5e GM is free to allow this kind of play, but [MENTION=97077]iserith[/MENTION]'s injuction about smoothness of play comes in. 5e has no mechanical systems or support for this kind of play, so it's entirely on the GM's continued approval and the table conventions. Perhaps this works well, but any such ad hoc system is likely to have more pain points related to it's ad hoc nature. In other words, absent mechanical reinforcement of this play in the system, exercising it is as reliant on GM approval as what you'd replace with it. Still can be an awesome game, though.
That said, I'm pretty loose with player introductions in 5e because I strive to use my GM "no" as rarely as possible. Still, there's a limit in play and an understanding at our table because there are no mechanics available to resolve a conflict. This is different when we play Blades, as there are those systems in play. I clearly notice, though, that my overhead in running 5e is much higher than in Blades because I have to do more heavy lifting on the content side AND be careful to maintain "fairness" with that content. In Blades, I just have to GM within the clear constraints and don't have to worry too much about "fairness" at all.