FAQ

Materia is one word that happens to mean everything MarrowMyth does.

It's the matter and substance that makes up a universe — the World Engines. It's raw material — historically, the source material from which other things are built and crafted — the heart of every commission. And in Spanish and Italian, materia means subject, topic, or syllabus — the Practical Engines, and the learning. One word that covers the World Engine, the Story Engine, and the Practical Engine all at once.

I'm obsessed with subject matter, source material, and substance. Materia is AI built for creatives, not against them — focused and trained solely on the source material you bring, devoted to its subject, and built to raise entire universes of story and learning out of it.

If Materia had existed when I was sixteen, it would have changed my life. As a reader, a writer, and a gamer, if someone had told me I could step inside the worlds of my favorite novels and games, I'd have lost my mind. I wanted to build — with the resources I have now — the exact thing I'd have killed for back then.

The push came with the announcement of Zach Cregger's new Resident Evil film. The disregard for the source material of one of my favorite IPs of all time pushed me past my limit, until I decided that if no one else would honor it, I would. So I started building the first World Engine: Resident Evil — a world I could actually inhabit, one that respects the source material, loves it, even exalts it and its characters.

I built that first engine for the same reason I wrote my first fanfiction (also Resident Evil, also at sixteen): because I wanted to exist in a world that stayed true to what made it great. Then more worlds came. Then it had a name. And it became far more than I ever expected. I built Materia because I needed it — it answered my own frustration, it solved my own problem. Now I hope to use it to solve yours.

Each of those is built for something different. Character.AI is for chatting with a character — a conversation, not a world: no place to move through, no consequences, heavily filtered, and the character tends to forget. AI Dungeon is the closest cousin — an open text adventure — but it's improvising, with no authored world beneath it, so it drifts, contradicts itself, and enforces nothing. ChatGPT is a general assistant with no world, no lasting memory of your story, and no systems — you'd do all the bookkeeping yourself.

Materia is the opposite of a blank improv box: every engine runs a fully authored world, and the AI isn't a chat partner or an improviser — it's a narrator held to the world's own rules that tracks your health, relationships, and every choice, and remembers. Make a mistake, you pay for it. If something dies, it stays dead. Character.AI gives you someone to talk to; AI Dungeon gives you a sandbox to improvise in; Materia gives you a real, consistent world to actually live inside.

Three families, one technology:

World Engines — total freedom. You're placed inside a fully realized world and turned loose; no script, no ending, nothing that loops. The widest scope of the three.

Story Engines — your story, authored. Closer to an interactive novel: you build the world and cast, and every choice carves out a personal playthrough, but the arcs are intentionally guided. It's your story, your characters — and it doesn't even require an AI.

Practical Engines — for learning and teaching. The same technology pointed at a subject: a patient, adaptive tutor for a language, a craft, or a full curriculum, that remembers a learner's level session to session.

The flagship engine is Resident Evil: Rebirth — a survival-horror experience set in an endless, Umbrella-engineered simulation of the Raccoon City incident, live and free to play. Fallout: The Windy Wasteland — a post-apocalyptic Chicago — is built and coming soon, with more engines in development. Visit the World Engines page for the full lineup.

No. The same engine that runs a living world can run a living classroom. Commissioned as a practical engine, it becomes a patient, adaptive tutor — for languages, mathematics, public speaking, or a craft like scriptwriting or songwriting — with replayable lessons, ever-evolving tests, and a progress tracker that remembers your level from one session to the next.

It's well suited to homeschooling, tutoring, training, and skill-building of every kind. The world it teaches is built around your curriculum, the same way a story world is built around your lore.

You could — but you'd be re-feeding every character, rule, and world detail with each message to stay consistent, burning tokens and still drifting. Materia holds all of that automatically, in a purpose-built interface — about 75% cheaper, far more consistent, and hands-off. You can also easily edit and add to existing lore, share your engine and world with others, and keep character and story consistency theoretically forever.

No. Materia is proprietary and not available for download, licensing, or independent use. It is built, maintained, and operated solely by published author F.C. Marrow. Available engines are accessible for public use directly through this website — no download, no installation required.

That depends on what you're after. Looking for an adventure? Jump into one of our current World Engines and see how far you can take it. Have a story to tell — or want to put people inside your world, or talk to the lead of your own novel? World and Story Engines are for you. A teacher, homeschooler, or just trying to finally learn something? Our Practical Engines are what you want. You can always use the Contact page to ask about specifics.

A few engines are free to jump into right now. The ones built on F.C. Marrow's personal original worlds are reserved for Patreon subscribers — and a subscription unlocks all of them, plus the locked Discord channels that reveal what the Materia engines are truly capable of.

Materia runs entirely in-browser with no installation required. While it can be accessed on mobile, the experience is designed and optimized for desktop use — with dedicated mobile versions in development.

Yes — forever. A commissioned engine is delivered as a local file that lives on your own machine, yours to keep and run with no membership, no subscription, and no dependency on my servers. The only ongoing cost is your own AI usage, billed by your provider.

Real-time multiplayer is something we're actively conceptualizing — exactly how it'll work is still up in the air. What you can do today: with the Materia Story Studio, you can share your engine and your world settings with others, so they can play your same story, your way.

A studio built right into the engine. Open it and you can shape an entire world by hand — write your own character, set the premise, lay out every location, and fill the cast with canon faces, people you’ve met in play, or someone entirely invented. You decide how each one feels about you before the story even starts, then save the whole world to a single file and hand it to a friend so they can play your version, your way.

Most AI stories are pure improvisation. Materia engines also carry hundreds of hand-written scenes — Authored Moments — that surface at exactly the right time: when you’re in the right place, with the right person, and your bond with them has reached the right point. A guarded character finally opens up, an old friend pulls you aside, an enemy forces a confrontation. They’re tied to who and where you are, they never repeat, and the well is deep enough that you could play for a year and keep meeting new ones.

Every character tracks a Bond and a Romance meter that move in real time as the story earns it. Cross a threshold — friendly, close, devoted, or a crush, smitten, in love — and the engine marks it with an Authored Moment that’s unmistakably that character’s. It runs both ways: mistreat or betray someone and the bond falls just as meaningfully — warmth curdles to wariness, wariness to open hostility — and a character who comes to hate you will act like it. In a safe place that’s cold, simmering friction; somewhere genuinely dangerous, a betrayed ally can turn on you outright.

Materia is optimized for Grok — engineered specifically for the most capable AI storytelling available. The configuration, system architecture, and narrative design are built around getting the best possible performance out of it. Every world we build is Grok optimized by default.

Other AI models are available as alternatives, but they are not optimal. The engine is designed and tuned for Grok, and the difference in narrative depth, consistency, and immersion is noticeable. For the best possible experience, Grok is the recommendation — and the standard every engine is built to.

API stands for Application Programming Interface. In plain terms, it's a key — a private code that allows Materia to connect to and communicate with an AI model like Grok.

Think of it like a utility account. Materia is the appliance. The API is the connection to the power grid. Without it, the engine has no AI to run on. With it, the two talk to each other seamlessly every time you play.

Your API key is unique to you, tied to your account with the AI provider, and should never be shared with anyone.

Yes. Materia connects directly to an AI model to power the narrator, and that connection requires an API key from the AI provider of your choice.

For the best experience, that means an API key from xAI — the company behind Grok. The engine is built and optimized around it. ChatGPT and Gemini keys will also work if you already have them, but the experience will not be the same.

The API key is separate from the commission cost. It is your direct account with the AI provider, and usage is billed by them — not by MarrowMyth. Costs are typically very low for personal use.

For Grok — the recommended option — go to x.ai/api, create an account, and generate an API key from your dashboard. The process takes a few minutes.

Once you have the key, you paste it into Materia when prompted — usually on the settings screen. The engine stores it locally and uses it automatically from that point forward.

Keep your key private. Do not share it. If it is ever compromised, you can revoke it and generate a new one from your xAI dashboard at any time.

For personal use, API costs are negligible — typically a matter of cents per session, not dollars. You are billed by the AI provider based on usage, and for the kind of narrative sessions Materia runs, that usage is minimal.

Materia is built specifically to keep these costs as low as possible. It uses a story compression system that condenses long sessions into compact summaries, dramatically reducing the amount of data sent to the AI on each exchange. The longer you play, the more that system works in your favor.

Most players will spend less on API costs in a month than they would on a single cup of coffee. It is not a meaningful expense for personal use — and MarrowMyth takes none of it. Every cent goes directly to the AI provider.

Through commission. You bring the concept — the IP, the setting, the tone — and MarrowMyth builds the world. Once delivered, that world is yours. Completely. You own it, you control it, and you decide everything about it — from its narrative direction to its content. MarrowMyth builds the engine. What runs inside it belongs to you.

Head to the Commission page to see how the process works, then reach out through Discord or the Contact page to start the conversation.

Three things: what you want, what you already have to build it (lore, art, documents, a curriculum), and what you'll use it for. Don't have it all figured out yet? That's fine — bring what you have and we shape the rest together. The conversation is part of the commission.

More or less, yes. Bring a world and I can build it — an original universe of your own, or one based on something you already love. Engines built around an existing property are private, personal, non-commercial tools for your own enjoyment; that underlying IP stays with its rightful owners, while anything original you bring or create remains entirely yours.

It depends entirely on what you want in it. World Engines are larger in scope but take less time to flesh out and more to hone; Story Engines are the reverse. Practical Engines come down to how deep you go into the subject, and anything with custom imagery takes longer. The more you want inside it, the longer it takes — and we set a realistic timeline together before we begin.

Pricing is discussed privately after your inquiry is reviewed. Scope, complexity, and timeline all factor in. Reach out through Discord or the Contact page to start the conversation — there's no obligation.

No. The engine is not a tool you configure or build with independently. MarrowMyth builds for you. If you have a world you want made, that's what commissions are for.

You do. The world commissioned is your intellectual property — your setting, your characters, your lore. MarrowMyth builds the engine that runs it. The world itself, and everything inside it, belongs to you entirely.

Your original world is your intellectual property — what you do with it, commercial use included, is entirely up to you. The one thing you can't sell is the Materia engine itself. And engines built around an existing third-party property stay strictly personal and non-commercial, with that IP belonging to its owners.

Commissioned worlds are built to your specifications with full creative freedom over setting, tone, and theme. A Materia Engine is a narrative framing device that runs on your own AI provider and your own API key — so the boundaries of whatever gets generated are set by you and your provider, not by us. Whatever the model produces in response to your inputs is yours alone, and your responsibility.

You have one hundred percent control over the tone and direction of your story — through your own inputs and your chosen provider. The engine frames the world; you and your provider decide everything else. Whatever is generated is your responsibility, not ours.

No. We store nothing and receive nothing — there are only two connections, you and your chosen AI. No one sees your sessions unless you choose to share them, which is exactly what the Story Export button is for.