Frederic Brown- What Mad Universe
Originally published in 1949.
Frederic Brown was a creature of the pulps, a master of several genres, with stories ready to go for whichever magazines was willing to buy them. When Keith Winton, the pulp editor hero of this novel, finds himself lost in an alternate universe where Earth is under attack by creatures from Arcturus, his first thought is to crank out a few adventure stories and sell them for quick cash. Of course attempting to sell his stories to a slightly different version of himself leads to trouble…
This is a fun satire of science fiction writers and fandom. Winton is the editor of “Surprising Stories” a sci-fi pulp in the mirror universe is an Adventure magazine, since SF conventions like Bug Eyed Monsters and space women in skimpy outfits are a fact of daily life. When he tries to find his New York City apartment he is lost in a nightly Mist-Out–a complete blackening of the city to mask it from Arcturan attacks. Though no one can see more than three inches in any direction, gangs roam the streets, arms locked tapping canes against concrete.
There are quirky details here. Winton tries to buy something with a 1928 quarter and a shopkeeper tells him the coin is worth a lot of money. But when he then produces a 1935 coin the shopkeeper calls him an Arcturan spy and starts shooting at him.
Very fun, though readers looking for hard SF may be disappointed–the exploited moon men and cultured Venusians date this quite a bit.