worlds from home...

Top Down vs. Bottom Up: The Middle Road

In Design Strategies, Written by Thomas on March 30, 2011 at 11:52 am

This week I’m going to fill you in on the strategy I’ve been talking about this whole trilogy: the Homebrew approach of mixing together top-down and bottom-up design. Wanna know how to have your cake and eat it too? Read on.

(This is the third article in a trilogy. Part one, on top down design is here, and part two, on bottom up, is here.)

You’ve got to be tough when deciding what tools you’re going to use in your work. Not too long ago I had a computer science professor who asked on the first day of class whether anyone had taken a strong stance on the ongoing Mac vs. PC debate. When a few people raised their hands, he said, “Then I advise you to ditch the unprofessional attitude and use whatever tools are best for the current problem.”

That attitude is what I’m talking about. Top down design and bottom up design are both just tools in your toolbox.

So how do you actually pull this off? The idea is not to somehow use both methods at once, but to recognize what situations they’re best suited to.

Take the Homebrew for example. It’s gone through several different phases. The first phase, about six years ago, was pretty much bottom up. My friends and I would have a cool idea and put it up on our forums. None of us had an overarching vision, we just had some neat stuff, and the Homebrew was a good place to store it. A lot of ideas that stuck around first surfaced here. For example, the Es’mensis, a group that has received a lot of care and attention, first appeared as a race summary created during this phase by my friend Frank Pierce. At the time they were strongly tied to the seasons; the season of your birth consigned you to a particular caste, and even had physiological implications. Since then they have been remade into a storied race, fey around the edges, obsessed with myth and the long hunt for a lost city.

(Notice how even though this is bottom up, the Es’mensis were still described as a whole race? This touches on an important consideration I’ll talk about in the “post script”, but the basic idea is that “top down” and “bottom up” are more about the direction you work in, from more abstract to less, or vice versa, than they are about what your building blocks are.)

Doing this might have been part of the reason the Homebrew has had such longetivity. Since we were primarily creating local content, we didn’t get committed to a large scale vision for the world that would cause us to abandon it when the vision had become stale.

The next phase was top down. Here we had all these random locations and events and characters, but it lacked coherence. So we built a cosmology and started to fit everything together on a grand scale. We developed purposes for nations, repositioned major events to make more sense with each other, and came to understand the most important histories of our world. We also resolved a lot of consistency issues that had arisen in the first phase. (In fact, coming up with aesthetically satisfying solutions to these inconsistencies was one of the hardest jobs we tackled.)

A lot of this took one of two forms: big charts where we outlined relationships and chronologies, and long discussions where we brainstormed the effects these events would have on one another. One issue that we tackled time and again was the nature of the Homebrew cosmos: who created it, why, and how? We pulled in everything we could as fodder for our creativity. We talked about history, religion, other fantasy worlds and what we didn’t like about them, and even occasionally science. We wanted a world that was internally consistent, and devising a sort of scientific view of the supernatural aspects of the Homebrew helped us make that possible.

We didn’t realize that in short time all of this striving for a “certain” answer to the nature of the world would be torn up and left floating, not as definitive facts about the world, but as fuel for stories. They became the roots of theories and opinions possessed by the world’s inhabitants, with no more inherent validity than any of the other competing schools of thought.

This change came about when, after a couple month sabbatical, we came back to our world and made a final, critical top-down decision: for its whole life, the Homebrew had been a world designed for roleplaying games, but from then on it would be a world designed for stories. Not just literature, but anything we could get our hands on. Music, film, anything. We realized that the real world doesn’t have the sort of definitive manual we had been working on, and so for the sake of verisimilitude we got rid of all the easy answers.

Since then we’ve moved on to a mixed phase that’s fueled by the many top-down decisions we made during phase two. (All of our “certain” answers are great starting places for stories.) Since our current goal is to tell tales, so we choose either top-down or bottom up depending on the premise. When Jeff and I started planning out a Wheel of Time-esque, 20 book epic, we started top down, identifying the major conflicts of the story, the groups likely to get involved, and the kinds of complications they would run into. Then we picked a cast of characters, some from our library of Homebrew personalities, some made up for the occasion. But when I work on telling the story of the Gloaming Man, I pretty much start with an event and build out from there. It’s only after I understand the episode itself that I situate in the larger context of the Gloaming Man’s meta-narrative.

I think this is a pretty intuitive way to handle things, and I suspect plenty of people work up and down like we do in the Homebrew. So are any such out there? And even if you’re not an up-and-downer, any comments or suggestions now that we’ve finished the trilogy? Is there actually a way to work in both directions at once? Is working in both directions really just distracting? I’d really like to know what you think.

This next part is a post-script. It’s not essential, and if abstract mumbo-jumbo makes you uncomfortable, you can turn back now and no one will judge you. But for those who care to brave it, it might provide a nice way to conceptualize what we’ve been talking about:

To put this all in perspective, you can imagine your world as existing at different levels of abstraction, or aggregation, and at each level you decide on some basic unit. So the lowest level of abstraction for people would take the individual as its basic unit. The next higher level might use families as the basic unit. Still higher levels would take cities, countries, or whole races as the basic unit. You get the idea. Geography, magic, language, anything can be thought of as having different layers like this.

As you proceed to higher and higher levels of abstraction, there is necessarily some compression of information as you treat larger and larger groups as units. But that compression is exactly why those higher levels of abstraction are useful. It reduces the amount of information you have to juggle.

So what does this have to do with top-down and bottom-up design? Both methods specify a certain direction through which to move through the levels of abstraction. Top down design goes from more abstract to less. Bottom up design is reversed, from less abstract to more.

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