I recently found a RPG called Kidworld and it reminded me of a book titled “The Girl Who Owned a City”. Penned by OT Nelson in 1975 it’s a short book in the post-apocalyptic (plague variant) genre. It is a YA book and fairly short, but Nelson really packed a good story in the book, dealing with children taking over a world devoid of adults, kinda like a global Lord of the Flies.
I came across a post at Livejournal that showed a letter from the book vs a letter from a Kidworld campaign. Both are pretty cool. Left is the book, right is the RPG.