Some Time Never: A Fable for Supermen

Sometimes Never: A Fable for Supermen is a 1948 Science Fiction novel by Roald Dahl. It is the first novel after World War II to mention the atomic bomb and the end of the world. The plot is divided into two parts, the wartime adventure of RAF pilot Peternip during the Battle of Britain and the plan of the Gremlin Leader to outlive humanity in an alternative Cold War.

This book contains the following tropes:

Alternate History
Apocalypse How
Everybodys Dead Dave: The Gremlin leader finds out if there's no humans, no one can imagine Gremlins, and so they cease to exist. Poof.
Expy: There is a charater named Stuffy who's completely an Expy of a character with the same name from Dahl's previous children-friendly Gremlin book, The Gremlins. It's the same with the other two protagonists: Peternip is Gus, Progboot is Jamface.
- In fact, this book itself is a Darker and Edgier version of it.
Genetic Engineering Is the New Nuke: In the book, there is a kind of virus that targeted only designated victims.
It Gets Worse: After all the humans on Earth kill each other, the Gremlins cease to exist, too because they are created by the imagination of the humans!
Kill Em All: See above. Roald Dahl had outdone Tomino!
Mythology Gag: The main food of the gremlins are snozzberries. They are later referred in Charlie and The Chocolate Factory and My Uncle Oswald. This word means "head of dick" in the latter.
Our Zombies Are Different: Roald Dahl is in fact the first person to suggest that radiation can make people mutate into zombies. Though he is Not Using the Z Word, just wrote that people became mad when they are exposed to radiation. Later, there are some virus developed to drive people mad and bite each other untill death.
Utopia Justifies the Means: The Gremlin Leader did create a peaceful world without class, money or machinery among gremlins after there are no humans.
Write Who You Know: Dahl himself had been a fighter pilot in the Second World War a few years earlier.
- Though not a nuclear scientist or politician.
You Fail Nuclear Physics Forever: Completely averted. Roald Dahl describes a nuclear blast in a suprisingly detailed and graphic way and how it "broiled" the protagonist alive. Also, he predicted the inventing of "dirty" neutron bombs.