ME: Specs with a lot of world building have a built in problem…
SOMEONE ELSE: Screw the rules! I’m not a hack like you! I’m creative! Enjoy riding your formula train to mediocrityville!
Okay, look, there’s no script god, and even if there was, he’s not going to strike you down for setting a story in the land of Elsenduff, where the Centaurs, the Ogres, and the Flitterkin have a tense, three-way alliance. World building is an effective tool in the screenwriter’s toolkit. That said, all scripts are a collection of choices. Each choice brings with it strengths and weaknesses. It’s important to understand what you’re signing on for.
1. Defining World Building
In a sense, all scripts take place in some sort of “unusual world,” even if that unusual world is a metaphor for the uneasy psychological territory the character finds themselves in after the plot incites an incident in the ordinary world.
Once upon a time there was a _________. Every day they did ___________. Until one day _______. And so… *Source – the oft quoted Pixar’s Rules of Writing post.
Breaking Bad rarely strays from New Mexico, but Walter White finds himself in a strange new underworld once he gets involved in crime.
Lorenzo’s Oil starts with ordinary parents. When their son gets sick, they must move heaven and earth to save him.
You get the idea. If these were fables, the characters would go to some Jungian underworld to seize some totemic sword. In modern times, they just suffer a lot, which usually forces some kind of change. The metaphorical world is not what people are talking about when they talk about world building.
All scripts have settings. The degree to which a setting takes a script into world-building territory is the degree to which it challenges our understanding of how things work.
Many fantasy/horror scripts use our mundane world, then lay a genre element over them. Ghost has ghosts. Wolf has werewolves. The X-Files, True Blood and Buffy have a plethora of weird things, but they exist in a recognizable real world. These are light on the actual world buidling part, but still have unusual stuff that needs to be explained.
A world-building script is a script where a new world is introduced, one that has different rules and customs, things that need to be explained.
Many fantasy scripts take a normal character to a new world. The Wizard of Oz. Alice in Wonderland. South Park’s Imaginationland. These have to explain the world, but they have an easy time of it, because there’s a relatable POV character to ask the right questions and react to things as a normal person might. If a character from our world finds himself in the Gravity Forests where rain falls upwards, they ground the reality by pointing out the unusual and reacting to it.
Then there are world building scripts where the unusual reality is the “ordinary” part of the story. These include – fantasy/scifi worlds like Middle Earth, the Star Wars Universe. Scripts that take place in the far future. Scripts that take place in the distant past (I accept that Weimar Republic existed, but if I see two gay guys kissing in the street, I’m going to need a little more context to understand how brave they’re being). If a trailer begins with “In a world,” odds are it’s one of these. The more out-there the world is, the more grounded it needs to be.
2. Explanation and Grounding
If an evil wizard has a ton of powers, there ought to be some explanation for why he can’t just wish our heroes dead. If a DeLorean goes back in time, you’ll probably want some plot-specific limitation on its crazy powers. You don’t always need to explain this (ghosts in movies like THE GRUDGE probably could just kill our heroes, but they don’t because… ghost reasons), but sometimes its necessary, even if the answer is silly. Movie explanations are less about explaining time travel,and more about some one in the scene having the presence of mind to at least ask about it.
This becomes harder in a world that’s removed from ours. Bilbo Baggins isn’t going to look out on Middle Earth and say, “Gosh, isn’t it unusual that I live on a planet with dozens of other intelligent species?” The story has to set up the rules, usually by showing, not telling. BAD: A title card says: In this world, cursing is the worst thing ever. BETTER: Cops chasing a serial killer give up on him to take down a guy who says “Damn.”
You can also ground a world via a character’s emotional reactions to things.
If Bob and Alice are humans in a magical world full of beings called Xdys, I’m lost.. But we can infer a lot about the world by how the characters react:
BOB: I saw a red Xdys.
ALICE: Sigh. Is it Monday already?
BOB: I saw a blue Xdys.
ALICE: Are you getting high again?
BOB: I saw a black Xdys.
ALICE: It… it can’t be. We’re all going to die. I… I’ve always loved you, Bob.
For more on this complex topic, read this: http://improvoctopus.tumblr.com/post/89935504418/emotional-heightening-component-game-theory 
3. Space Constraints
The problem with this exposition and setup is that it takes up a lot of space. In any story, your first act has to establish character relationships and what each of their deals is, and you’ve got to set up high concept props, stakes, and other stuff. In a worldbuilding story you have to do all that, plus the setup for the world. This will usually require more space.
Here’s where someone’s going to say, You hack! There are no rules! Why should I restrict myself to 120 pages or less? Did you know Reservoir Dogs was 131 pages?
To which I say, sure, do what you want. We’ve already discussed the absence of a script god. But still…
The page restriction is a cultural bias. The bias might be silly, but it exists and should be accounted for. A good, but unknown writer who writes a 131 pages might need every goddamn line to tell his amazing story, but he ends up ghettoizing himself into the same category as the dozens of terrible writers who don’t know how to edit themselves and don’t understand how perception influences opinions.
Putting it another way, the page limit is like a salary cap in the NBA or NFL. There, teams can only spend so much on player salary, or else they incur penalties. The salary cap is a written rule intended to prevent rich teams from buying all the stars. The page count is an unwritten rule that prevents readers from having to read 151 page drafts (gotta draw the line somewhere).
People can and do go over 120 pages, but there’s a penalty. You risk a reader’s goodwill and faith that you know what you’re doing.
Putting it a different way, the longer your script is, the more you’re raising the bar for yourself. If you’re going to inflict a 131 page draft on someone, there’d better be a damn good reason for every line, and it had better be as good or better than Reservoir Dogs. Good luck with that.
Given all this, setting up a world takes away valuable pages that might be better served elsewhere. Like in telling a great story, writing a moving scene, or just slowing down the rhythm of a plot and creating some blessed white space.
4. World building is secondary to telling a good story, entertaining people, whatever you want to call it.
You might have a great fantasy world, a well-researched period piece, or an exceedingly complicated set of alliances. God forbid, you might even have all three in the same script.
Unfortunately, not everyone is going to find the Elvish Language/1920’s Paris/the Trade Federation as interesting as you do. Bad worldbuilding scripts inflict themselves on the reader, like a 1980’s comedy character who wants to show you vacation slides.
The trick is to write a story that’s so good that it will appeal to someone who might not even like the genre or setting (Game of Thrones and Star Wars are great at this. Star Trek has always struggled with it).
Simply put – if you’re going to spend 25-30 pages making me learn the rules, minutia and trivia of your make-believe fantasy land, there had better be some damn good payoff for it. I don’t want to learn new things so I can be lectured on genetics, go on a travelogue to imaginary places, or learn about the political structures of non-existent governing bodies. I want something awesome.
The world and exposition of Star Wars enables this awesome stuff:
- Using the force
- Awesome space battles that look suspiciously like WWII
- Darth Freaking Vader.
The world and exposition of Game of Thrones enables:
- Trial by combat
- The Battle of the Blackwater
- Ice zombies attacking the realms of men.
- Intrigue and investmen (one of the many reasons why the franchise works better in TV than it would as a movie)
- Tyrion Freaking Lannister
The world and exposition of Harry Potter enables:
- The Chamber of Secrets
- Tom Riddle’s evil diary
- House elves, time turners and the Deathly Hallows (okay, bad example).
- Severus Freaking Snape
A bad world building script enables
- More world building!
- Scenes of people talking that might actually be better if they were talking about anything other than the world.
- Fight scenes that become boring because it’s not clear what weapons can hurt what armor.
- Lots and lots of names and genealogy that have nothing to do with the plot.
- Dense and crammed pages because the author prioritized putting a ten line speech explaining stuff on every other page instead of investing that space into action, character, or anything moving, investing, or fun.
5. In Closing
World building is not storytelling. World building is only useful to the degree that it allows the story to do awesome things that wouldn’t be possible without it.
You can do anything you want in writing, you’re just making a series of choices. If you’re going to make a big choice on the world, it’s important to know the pros and cons of that choice. Or ignore everything I just said. It’s your damn script.