Not design specifically, but I wonder if there's a large section of modern audiences that have active disinterest or even vehemently against verisimilitude as a goal or reason for rulings/rules design
I think that verisimilitude remains important for modern audiences but it's hardly uniform. While it is a trite point for me to make, everyone has different stress points when it comes to what disrupts our sense of verisimilitude. And to be somewhat cynical, I suspect there is no small part in people's sense of verisimilitude in TTRPGs being coincidentally disrupted when the situation happens to be to their disadvantage as players. (With some players, IME, being perfectly willing to gloss over notions of verisimilitude when it transpires in their favor or advantage.)
I also think that different cultures of play have different approaches and attitudes towards verisimilitude. For example, in even narrative games, there are often principles directed at the GM to breath life into the world in a believable way, respecting established fiction, or beginning and ending with the fiction. Even "follow the fiction" regarding consequences can be read as an appeal for verisimilitude. And when it comes to narrative games, GMs or players generally can't introduce new fiction that contradicts previously established fiction.
Where there is "friction" in approaches tends to rest in what are perceived as causal processes. Narrative games are often designed to create moments of drama for players characters, often engaging with theme and premise. But other play cultures may perceive these games processes as "artificial" when it comes to what is transpiring in the fiction and disruptive to their
subjective sense of verisimilitude. And as previously said, people have their own idiomatic disruption points when it comes to verisimilitude. For example, one person may be fine with a wandering monster check producing a quantum ogre while playing a dungeon-delving OSR game but not fine when the GM narrates the arrival of quantum ogre after they fail with Fear with a check in Daggerheart. But it may also be because they have internalized the "logic" of wandering monster checks through 40 years of playing D&D, but have little to no experience with narrative games, which can be contribute to their sense of verisimilitude disruption.
All that said, I am
one-hundred percent sincere when I say that I have experienced a much greater personal sense of verisimilitude in my games of
Stonetop than I have in all of my games played of D&D over the past twenty-odd years.
That relates to the last item on the list.
Good point, Crimson. However, I wasn't necessarily thinking of PC/NPC mirroring. Instead, I was thinking of the earlier point about simulation through mechanics vs. simulation through the fiction.
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As an aside, I also wanted to potentially make it a +Thread for Simulationism so there would be a place for people to also talk positively about Simulationist games (and hopefully not negatively about non-Simulationist games either), with a focus on the contemporary landscape. As I said before, I think that any perceived hostility to simulationism in contemporary trends tends to be exaggerated, if not imagined. Just because other games may have different play agendas doesn't mean that they are hostile to play agendas that they don't emphasize. I do think that there are a LOT of contemporary simulationist games, as well as older simulationist games that remain highly popular. But I also don't necessarily think that Simulationist games have to look like one thing anymore than all narrative games have to look like PbtA. Though I do agree with Snarf in so far as when I think about simulationist games, I definitely don't think D&D, whose simulationist elements IMHO seem more perfunctory or token.