If you only do one thing before you start naming cities, do this.
If you’ve found this post and haven’t read the worldbuilding one yet, here’s a quick refresher on where this fits in for worldbuilding. Genre and theme are the start of your journey. This article is the deep dive on that foundation. If you get this right, conflict becomes easier to choose, and the setting becomes easier to design without feeling random.
Genre isn't just a label, it's a tool. Genre sets expectations for:
Here are a few broad genres and what they naturally push you toward:
You don’t need the perfect genre label. You need a genre that gives you useful constraints.
Theme is the idea your world keeps asking questions about. Theme answers the following questions:
These come up in worldbuilding constantly:
A strong theme is something you can test in a hundred different scenes without repeating yourself.
Your goal is a 1–2 sentence foundation you can build on.
Use this template:
“This is a [genre] world about [theme], where [core experience].”
Examples (mix and match):
If your style statement doesn’t clearly suggest what life feels like in the world, tighten it.
Remember that genre and theme aren't just concepts. These are filters that you're going to use for decisions. You want to use them to choose what belongs. When you're unsure about an idea, you want to ask if it matches the genre's expectations, if it reinforces the theme, and whether it would feel out of place next to everything else. If the answer is no, then you want to either cut it or save it for another world if it's a really good idea.
You also want to use them to generate constant pressure. Theme becomes real when it creates repeated pressure.
Example: Theme = power
When you're building, answer these questions. Now any town, faction, or culture you invent naturally snaps into place.
Genre and theme can also be used to shape tone without overwriting things. Genre can control tone so that you don't have to force it with your description. If your genre is “cozy,” your danger feels different than “grim.” If your genre is “mystery,” your world hides information on purpose. Tone becomes automatic when you have a clear foundation.
If you're just starting out, then try to pick one primary theme. Most worlds can support multiple themes, but early on you want to choose one main theme and optionally add another one later. This keeps your foundation clear and makes the world easier to expand.
The following are a few examples of genres combined with themes. This might help you come up with your own unique one. Don't worry if you feel like a genre and a theme combination has already been used. There's always room to mix things up with the "Style Statement.”
Mistake 1: “Theme” is just an aesthetic word
One common problem that I think a lot of people might have with “theme” is that they'll use it as just an aesthetic word. If your theme is darkness or grit, that's tone, not theme.
Fix: Find a way to turn it into questions.
If you could turn it into questions, it would become easier to keep something as a theme. In the example given above, "darkness" is no longer just an aesthetic word.
Mistake 2: Too many genres at once
Another common mistake is trying to stack too many genres at once. If you put five genres together, nothing has any weight. Your conflict needs a solid foundation to build on.
Fix: Pick a primary genre, then add one modifier.
Mistake 3: Genre says one thing, the world does another
This mistake is one that people make when they aren't letting the genre define the world. If your genre implies grounded rules but the world behaves randomly, it feels inconsistent.