Setting is important, to one degree or another, in just about any work of fiction. But the genres of fantasy and sci-fi need something a bit heftier than a mere setting of the scene. In this post and the next one, I’m going to cover a few basics of the specific sort of scene-setting known as world-building.

In the genres of fantasy and science fiction, basically anything goes. But even in these and related genres (dystopian, paranormal, etc), there are guidelines that should be followed for the story to hold together and be convincing.

A fantasy world does not have to be “realistic” in the sense that it resembles our own world, but it should have its own set of rules, and things that happen in that world need to happen in accordance with these rules.

Inaccuracy or inconsistency of details are things that savvy readers will notice. Sci-fi and fantasy readers especially can be a nit-picking, detail-oriented bunch (or, at least, I am. And I’m sure I’m not the only one).

1. Natural Laws

Gravity, weather, the day-night cycle, the behavior of animals in their native environments—nature follows a set of laws in our world, and in a fantasy world it should do the same.

Let’s say your sci-fi story is about human colonists on a planet that orbits very close to its sun, so the surface temperature is hot enough to liquefy steel in minutes. If their space ships can barely survive long enough to land and take off again, then a lone human parading around in a space suit isn’t going to fare any better.

Are the humans’ colonies deep underground? Do they live in mobile cities that travel at the same rate as the planet’s rotation, so they always stay on the cooler night side of the planet? Even though the story is not “realistic” in the sense that it’s our world here and now, it needs to be realistic in that setting.

2. Cultural Laws

This one gives the writer more leeway than natural laws, in my opinion. You can set up your culture of fairies or aliens or gothic kingdoms any way you want. Religion, clothing, dinner table customs—go nuts and be creative! The most important thing about cultural laws is making these traditions laws within the story, and sticking to it.

In The Silver Chair (of The Chronicles of Narnia), when the main characters are eating dinner at the giants’ mansion, it’s revealed that the venison served had been a Talking Stag. Killing (and especially eating) a Talking animal amounts to murder of the highest degree in Narnian culture. The giants’ complete disregard for this cultural law makes them an abomination to the Narnians.

In several of the Narnia books, the subject of killing a Talking animal—even in self defense—is mentioned. The consistency of this cultural law throughout the series adds depth and believability to the world.

3. Avoid Deus ex machina

This is the “move of God,” or a surprise ending where an unexpected superpower sweeps in and miraculously fixes everything. Deus ex machina can occur in any genre, but fantasy and sci-fi can be particularly susceptible.

If your urban fantasy story is about clan warfare between different vampire clans in the city, and you’ve written yourself into a corner where the only way to stop the war is to sacrifice the main character, you have one of three options.

You can kill off the main character, and pull at your readers’ heartstrings (or possibly incur their wrath). You can go back and do some major rewriting, so that the tension and drama and resolving of the conflict challenges the main character but doesn’t kill him. Or, you can have some aliens abduct the rival clan and take them to another planet, thus halting the war.

That third option would be a Deus ex machina, and should be avoided at all costs. If aliens are already part of the story, or have been hinted at and foreshadowed effectively, then maybe you could get away with that sort of ending. But if the story is about vampires, humans, and more vampires, then suddenly bringing in aliens to solve the problem cheapens the story and confuses the readers.

I’ll continue this list next week. Any thoughts about these world building tips? Any dos or don’ts you’d like to add?