Let’s say a middle-aged librarian/writer had never played a video game. This person loves stories, language, and history and is not comfortable with graphic depictions of violence. This person would like to be immersed in a story that is also a game, and would prefer not to buy a whole bunch of stuff or acquire an entirely new skillset.
What’s the one game you would recommend?
@Julie try “80 Days” (https://apps.apple.com/us/app/80-days/id892812659 or https://play.google.com/store/apps/details?id=com.inkle.eightydays), i think that’ll fit the bill. it’s based on the Jules Verne story but does not follow the existing narrative strictly, and there’s lots of branching story threads to reward repeated playthroughs.
‎80 Days

‎*** Four BAFTA-nominations -- TIME Game of 2014 -- IGF Award for Narrative Excellence -- IMGA Award for Narrative -- DICE nominated *** "We’ve been dreaming about this future for decades. Guess what? It’s here." - New York Times *** "Interactive storytelling as its best" - The Guardian *** 9/10 Edge…

App Store
@hakamadare Oooh! I didn’t know there were games based on classic novels!

@Julie the publisher, inkle, specializes in that sort of thing.

in making a recommendation, i inferred some additional constraints from your initial request:
* “don’t need to buy additional equipment”, to me, says “restrict to games that run on a phone”, fortunately there are many such
* “don’t need to learn a new skillset”, to me, says “no games based on reaction time or eye-hand coordination”, which helps narrow the field

@Julie
my also-rans were:

* The Banner Saga (https://en.wikipedia.org/wiki/The_Banner_Saga), which i did not recommend only because it absolutely does involve violence
* A Short Hike (https://en.wikipedia.org/wiki/A_Short_Hike), which is not on mobile devices and which does require eye-hand coordination, but which i found utterly charming

The Banner Saga - Wikipedia

@hakamadare It could run on a laptop, but I don’t want to buy a gaming system for something I may play a few times, then lose interest in.
@Julie ah, ok then, that makes sense. in that case i more strongly recommend A Short Hike (buy/download at https://adamgryu.itch.io/a-short-hike), and while i'm at it, let me add a recommendation for Dorfromantik (https://toukana.com/dorfromantik/), which is farther from your initial criteria since it's more of a puzzle/strategy game, but i urge you to take a chance on it.
A Short Hike by adamgryu

a little exploration game about hiking up a mountain

itch.io