Dieselpunk

Dieselpunk is a retrofuturistic subgenre of science fiction similar to steampunk or cyberpunk, combining the aesthetics of the diesel era with retrofuturistic technology. The diesel era coincides with the interwar period, 1918 to 1939, and game designer Lewis Pollak coined the name in 2001 for his tabletop role-playing game Children of the Sun. Scott Westerfeld draws the border with steampunk at World War I, "the dividing point where modernity goes from being optimistic to being pessimistic"; Len Deighton's SS-GB and Philip K. Dick's The Man in the High Castle are considered dieselpunk by some, and Tim Burton's Batman (1989) has been referred to as a dieselpunk movie.

For writers it is steampunk with the optimism drained: fix one technology level (diesel engines, early electronics, Art Deco styling, noir ambience), keep it consistent across the work, and lean toward alternate history. The machines' limits are world rules the readers will audit.