I’m embarrassed to say that I have encountered this, this particular type of story on multiple occasions… So I got curious, is there a name to this trope?
Assuming it’s a surprise, this is Earth All Along. Genre Shift is similar, but that’s more about tone than plot
Specifically the After the End variant
https://tvtropes.org/pmwiki/pmwiki.php/Main/TomatoSurprise is the wider trope
Thanks! I think this is it… because I guess the more important part to this trope is that “hehe this is actually the world that you - dear viewer - lives in”… the high-fantasy part is secondary and depends on the genre I guess.
I think the trope From Cataclysm to Myth actually fits better. It even says in the description "Cousin to Earth All Along, but a premise or a plot twist rather than a Twist Ending. "
I have no idea the answer to your question, but I now know like 99% of people on lemmy have shitty reading comprehension.
Seriously. There’s a dozen links to TvTropes and almost none of them match OP’s description, but they’re all upvoted to high heaven. Not to mention the unrelated replies talking about their favorite stories which don’t actually match the trope either.
The TvTropes links are mostly right though? It matches the third variation of Earth All Along. The linked examples match what OP is describing except not being restricted to Fantasy.
Well OP didn’t specify Earth. I can think of some stories where it transitions from high fantasy into sci-fi but is not set on Earth, which is definitely not under the ‘Earth All Along’ trope.
Spoiler:
The Gods are Bastards is the first one that comes to mind, where it turns out the planet is a colony in an unstable part of space that’s been quarantined by the original science team who have ascended.
I knew a tvtropes link was going to be here as soon as I saw the question lol, here goes my next three hours I guess
Aladdin (1992). The Genie is the last survivor of the AI wars and has mental damage. The Cave of Wonders is another remnant. “Magic” is low level AI responding to human intent. Iago is an uplift. Agrabah is literally a generic Middle Eastern country because it was assembled from the fragmented records of what remained of the Middle East.
The Adventures of Brisco County, Jr. is my personal favourite of Bruce Campbell’s work. Starts off as any ordinary western, before getting very, very weird.
https://www.imdb.com/title/tt0105932/
Come to think of it, Firefly might count, after watching Serenity at the end of the series.
I just saw a video on the show on the youtube channel Secret Galaxy, pretty interesting, as I remembered the show, but never knew what happened to it: