A World Engine is a fully realized fictional world made playable. Materia takes a universe — its setting, lore, characters, rules, and tone — and turns it into a living space you can step inside: make a character, walk the world, speak with the people in it, and live a story that is truly your own.
Powered by Materia, the narrator drives the story. It tracks your character’s condition and relationships, remembers every choice, and holds the world accountable to its own rules. If you earn someone’s loyalty, they remember it. If something dies, it stays dead.
Every World Engine is custom-built for a single universe — its interface, atmosphere, and systems themed from the ground up. No two are alike. Play F.C. Marrow’s worlds for free, or commission your own.
What It Does
The engine takes your fully realized world — its setting, characters, lore, and rules — and brings it to life. The AI simultaneously serves as narrator, game master, and living author. It tracks health, relationships, and consequences in real time. Nothing resets. Nothing forgets.
What It Isn't
Not a downloadable game. Not a generic chatbot with a theme slapped on. Materia is proprietary technology — custom-built for each specific world. You shape your character, the lore, and the story. Once inside, you drive it. The engine brings your vision to life — lore-accurate, consequence-driven, and fully yours.
Eidetic Memory
Full world memory and consequence tracking. Characters, places, and choices stay consistent across a whole campaign. Nothing resets. Nothing forgets.
A Living Cast
Characters with their own personalities, tastes, and relationships — and they remember how you treat them, turn after turn.
Emergent & Custom Cast
The story invents people as you go — canonize the ones you love into permanent cast, or build your own from scratch.
Shape the World
Add your own characters and locations, bring your own art for portraits and your own audio. The world bends to you.
Build a Whole World
Materia Story Studio walks you through building your character, a full cast, places, and lore — then exports one file you load into the engine. It’s all added on top of the world that’s already there, never overwriting it. No technical know-how needed.
Edit, Delete, Regenerate
You’re the author. Rewrite any moment until it’s right — nothing is locked in against your vision.
One-Click Story Export
Leave with your entire run as a clean, formatted manuscript — the story you lived, captured and kept.
Custom-Built & Themed
Bespoke UI, visual theming, sound, and atmosphere — crafted to match each world, end to end.
Runs In-Browser
No installs, no downloads. Bring your own AI provider — your key, your rules, and your content stays yours.
For Creators
Your World, In Your Audience’s Hands
Your fans love your characters — but all they can ever do is watch from the outside. A World Engine of your own changes that. It takes your universe — your cast, your settings, your lore — and turns it into a place your audience can actually step into: make a character, walk your world, talk to the people you created, and live their own story in it.
Ten minutes of watching becomes hours of living. Instead of consuming your work, they bond with it — one session at a time. And because the AI plays your characters in-character and the world remembers everything, it always feels like yours.
Turn Followers Into Residents
Passive fans drift; residents come back. Give your audience a branded world they can live in — and a reason to keep returning to you. Every session is time spent inside your IP.
You Stay the Author
The engine honors your canon and plays your characters true — never a generic chatbot. You set the universe; your audience gets to live in it; and your world stays entirely yours.
In Action
See It Running
RE: Rebirth — live on Materia
Fallout: The Windy Wasteland — live on Materia
FFVII: Reclaimed — live on Materia
Available World Engines
World Engines built by F.C. Marrow, free to use with your own AI key. More are on the way.
A never-ending, Umbrella-engineered simulation of the Raccoon City incident — survive the outbreak, die, and wake to do it all again, the loop slowly fraying everyone caught in it. Play an original survivor, or a familiar one.
Explore →
A post-apocalyptic World Engine in the irradiated ruins of Chicago. Vaults, the Brotherhood of Steel, ghouls, raiders, and rolling rad-storms. Build your survivor and write your legend.
Explore →
The Summons rise to reclaim a world once theirs — and wage war on the Weapons.
Explore →
An original dark fantasy where the boundary between humanity and something far older grows thin. The moon is always watching. The affliction spreads.
Explore →
A world of storms, open water, and the things that move beneath the surface. Sail, survive, and let the sea decide your fate. Some ports offer shelter. Most do not.
Explore →
An original science-fiction world of altered consciousness, synthetic life, and the question of what remains when everything familiar is stripped away. The Seed broke. Something else grew.
Explore →
A breathtaking original world built on movement, freedom, and the things carried on the wind. Not everything that travels is lost. Some things are looking for exactly where they land.
Explore →Step Into a World
Enter the selector to preview each world in motion — or commission a World Engine built entirely around your own universe.