Worldbuilding an Alternate Earth Setting

Is your favorite worldbuilding phrase “What if?” 

• What if magic suddenly emerged… but technology stopped working?
• What if the allies lost World War II?
• What if humanity colonized Mars and the asteroid belt? 

If these questions really get your creative wheels spinning, then YOU should consider creating an alternate earth setting! 

It’s one of the 4 basic blueprints of worldbuilding—which we cover in another article. But today, here's a checklist of what you actually NEED to worldbuild your alternate earth… and what you can skip for now. 

Get ready to slide with into a parallel universe of storytelling inspiration! 

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Alternate Earth Defined (Plus Examples!)

So what IS an alternate Earth setting? That’s easy. It’s our world, with a TWIST. Somewhere in time—past, present or future—something went very differently. The world diverged from the expected path, creating a new branch of reality. 

You see this kind of worldbuilding everywhere, from the atompunk dystopia of Fallout to the utopian universe of Star Trek. Maybe it’s a world where magic ascended—and technology either didn’t develop, or suddenly failed. Or maybe it’s a place where people suddenly developed superpowers, or settled among the stars.  Alternate earth is the worldbuilding blueprint for many scifi and fantasy subgenres, including hard sci-fi, most "-punk" genres (steampunk, cyberpunk, solarpunk), gaslamp and historical fantasy, and (obviously) alternate history.

If it’s recognizably our world, just with a major change, you’re playing in the alternate Earth sandbox. 

‍Examples of Alternate Earth worldbuilding:

• Fallout
• Star Trek
• Gail Carriger's Parasol Protectorate
• S.M. Stirling's Emberverse
• Ilona Andrews' Kate Daniels series
• Revolution
• Terra Nova
• The Expanse
• Many superhero worlds

Where to Start Worldbuilding

Your starting block is the Divergence Point. That’s the moment when your world split from ours. And you need to nail down three things: when it happened, what changed, and the world’s response. 

First up, WHEN did the divergence happen? In our past, present, or future? Ancient Egypt? Last Tuesday? Next month? Five hundred years in the future?

When you’ve settled on that, ask yourself WHAT went differently? What actually changed? It can be as simple as a battle having a different outcome, or as dramatic as the rules of physics suddenly changing. Maybe aliens arrived, or someone invented limitless clean energy, time travel, or teleportation. 

Once you’ve nailed down what changed and when, think through how the world—or part of it—responds and changes. Not just the immediate reactions, but the long-term consequences. 

These three questions provide the foundation for your alternate earth. Everything else flows from there. 

But! There are a few things you should focus on first, so your setting is built to support your story. 

‍Essential Questions

• Where to Start: The Divergence Point
• When: Past, present or future?
• What: What went differently? What changed?
• Response: How does the world respond?

Taking It Further

Once you have those essential questions answered, it’s time to build out your world! 

First, you’ll need to outline a basic timeline. How did you get from your divergence point to the story’s “now”? What were the key events of this new reality? What would every schoolchild know about their world’s history? 

A basic timeline helps you connect the dots and figure out the ripple effects. You don’t need every detail yet—just the major milestones. World Anvil’s Timeline feature can help! Use it to map out your alternate history. You can link events to articles, track multiple storylines, and visualize how your world changed over time. 

Of course, it’s still our Earth, so some things will be familiar while others are completely changed. What will feel recognizable to your audience—and what’s totally new? Think about culture, geography, language and transportation. If you’ve added magic to the mix, or advanced technology—like faster than light starships or steampunk airships—make sure you include that as well. 

And don’t forget conflict! How did your divergence point create new factions, alliances, or rivalries? Maybe a nation that fell in our timeline is now a superpower. Maybe a new religion emerged. Maybe corporations run everything. 

World Anvil’s diplomacy webs let you visualize relationships between the power players in your setting—you can see which factions are allies, what organizations are enemies, and what secret cabal is plotting to take down everyone else!  

Lastly, you’ll need to think about your world from your protagonist’s point of view. Who is your main character? What’s their everyday life like? This is often where you can employ “show don’t tell” storytelling. Your audience will automatically compare your main character’s world to ours. Is it shockingly different? Subtly changed? Dystopian? Utopian? This is how your setting becomes REAL to them.

‍Your Alternate Earth Checklist

• A Basic Timeline
• Same vs. Different
• Factions & Struggles
• MCs Status Quo

What Can Wait?

Here’s the good news: you don’t have to figure everything out right from the start. You don’t need to know every single butterfly-effect consequence of your change—broad strokes are enough. Focus on your foundational points—the changes that directly impact your story. 

You also don’t need to go crazy trying to plot every single event from the divergence to now (or from now to the divergence in future-set scifi). Start with the critical moments, and fill in the gaps as you need them. And while global scope is fascinating, you shouldn’t start there. Focus on your story’s immediate location first, plus any major factions or powers that will directly affect your plot. The rest can come later. 

Back to Reality

So now you’re ready to split the fabric of reality! 

To worldbuild an alternate earth setting, you NEED a divergence point, a basic timeline of major events, a “day in the life” picture of what’s different and the same, some factions and their conflicts, and an understanding of your protagonist’s status quo. 

Start focused, build outward, and let your world grow naturally. 

And if you're looking for a worldbuilding platform to help you keep your work organized, be sure to check out World Anvil. You can create a free account, and explore our full set of worldbuilding tools.