The world of Girl Genius is a world ruled by "Mad Science" -- which isn't really science, but rather science fantasy. There's nothing wrong with science fantasy, Star Wars uses it all the time. Specifically, Girl Genius is set in a 1900-ish Europe that uses a Newtonian kind of pre-petrol mechanical technology: think the machines from Flash Gordon, only substitute the nuclear power and gas with wind-up springs and coal. For medical technology, think Victor Von Frankenstein, with a few (essentially) magic potions thrown in.
In terms of aesthetic, think Jules Verne and Alphonse Maria Mucha -- Oh; remember Princess Leia from Return of the Jedi? (Did I mention the (mostly) cheese- and (not quite as much but still nice) beefcake?) -- with a little bit of Art Deco on the edges. This is probably the appeal of Girl Genius -- the romanticism of the late 19th and early 20th century, and artistically (or divinely) inspired but ultimately knowable technology.
Turning away from the physical world building, we come to the social setting. In Girl Genius, Europe (excluding England) is held together by a despotic overlord. Vassal barons and princes administer local fiefs. So that's another reader hook: The Age of Empire! Hey -- wait a minute; what other science fantasy story had an Empire ?
The society is stratified as follows:
- Sparks -- these are genius scientist: might be good, might be bad, but they're definitely crazy (it's the "Mad" in "Mad Science")
- Royalty -- It seems that a large number of royals are also sparks.
- Minions -- Non-sparks; the go-fers.
- Jägermonsters -- mutant, jar-head, vaguely Germanic, comic cannon-fodder. Think flying monkeys, only with no wings. Think Klingons, only more slap-stick.
- Other specialized soldiery -- it seems every other little kingdom or spark has its own, pseudo-Balkan legion of costumed military.
- Local peasantry -- somebody's got to be conscripted into the armies or at least form a torch-carrying mob.
- Constructs -- think cousins to Frankenstein's Monster
- Clanks -- in-world slang for semi-autonomous (steam or spring-driven) mechanical devices
In terms of Story Goodness, it's fun to read about Special People doing Special Things. The down side is that it can lead to a focus on The Chosen One. Girl Genius attempts to defuse The Chosen One Syndrome by having conflicting prophesies and information.
Having a stratified society means many story elements revolve around the characters discovering, redefining and rediscovering power relationships.
Zooming in from the cultural to the individual characters, we're never completely sure if a character is someone bad trying to be good, or someone good trying to be bad. The only thing we're mostly sure of is that most of the major characters, who are almost all sparks, are slightly crazy (or have a fanatical devotion to something). Probably, good versus bad is the wrong metric; a closer one would be self-centered or other-centered. The sparks are still mostly crazy, though.
Part of this moral ambiguity is that, in addition to power relations, no matter what social strata one comes from in Girl Genius, one has An Ulterior Motive:
- Finding the Lost Kingdom
- Finding the Secret Power Artifact
- Returning Home
- Total World (or at least European) Domination
- Clearing the way for a vaguely messianic person
- Keeping the Secret Identity a Secret
- Destroying, Containing or Subverting a Perceived Threat
Now add on a few Dysfunctional Family Dynamics:
- My Dad is a Ruthless (Benevolent?) Despot
- My Mother wants to possess me so she can further her evil plans to rule the world
- My Single Parent is too busy with Byzantine double-crosses to pay attention to me
- My Sibling has become a cyborg
- My primary caregiver is a ravening control-freak who makes modern-day helicopter parents look like permissive hippie-'rents.
- Our family had to create its own version of a witness protection plan
Throw in cheesecake, beefcake and meta-reference,... and... serialize !
Oh, right -- and, like Star Wars, there are huge machines blowing up in the middle of battles. (Hmm; Star Wars, only with dirigibles...)
Can't forget that.