Both in terms of the visual style and the mannerisms of the genre, the basis is the
There are no airplanes; there are dirigible lines. Some stories have robots, but they’re clockwork automatons.
Guns exist since gunpowder does for centuries. For the genre, they tend to be pistols, shotguns, and rifles. There are no automatic weapons or machine guns — though prototypes of these things might exist for the story.
This gives me an idea for a list to come soon: a list of Steampunk-themed properties.