Where Every Story Is Yours to Write

Synthasia is a text-based RPG where an AI Game Master reads your world — your character, your inventory, your surroundings, your history — and generates what happens next from all of it. Not scripted choices from a menu. Not a chatbot improvising in the dark. A genuine intelligence that understands the situation and responds to you, specifically.

Every decision leaves a mark. Every conversation could go anywhere. And the actions available to you are always a product of who you are and what the world around you makes possible.

An AI That Reads Your World — And Thinks Inside It

Before proposing a single action, the AI reads everything: your character's personality, skills, and backstory. Your inventory. The location you're standing in, what's in the room, who's present. Your history with every NPC. The world's lore, tone, and rules.

Then it generates options that make sense for this character, right now, in this exact situation.

Play a reckless mercenary and you'll see bolder, more aggressive options. Play a cautious scholar and the same situation reads differently. Carry a lighter into an enemy base where a gas canister is sitting in the corner — the AI might propose lighting it. The option exists because you have the lighter, this room has the gas, and your character is the kind of person who'd think of it.

The engine then runs the mechanics — the dice roll, the skill check, the consequences — and the AI narrates what actually happened. The creativity is emergent. The outcome is real.

• Context-Driven Actions — What you can do is shaped by who you are, what you're carrying, and what's around you. Options emerge from the world, not from a fixed menu.

• Character-Aware Proposals — An adventurous character gets bold options. A cautious one gets careful ones. The AI reads your archetype and plays to it.

• Mechanics-First Outcomes — The engine resolves every action through real rules before the AI writes a word. Dice rolls, skill checks, consequences — all real, never improvised.

• Configurable AI Stack — By default, Synthasia uses purpose-matched models: more analytical for game logic, more creative for narration and dialogue. Power users can assign any LLM to any individual task — one model or many, optimized exactly where it matters.

NPCs remember you. Reputation travels. The world reacts — not just to what you did, but to who you're becoming.

Any Genre. Any Era. Any Story.

Synthasia isn't locked to one setting. The same engine that runs a medieval dungeon crawl runs a neon-soaked cyberpunk thriller, a Cold War spy drama, a cosmic horror mystery, or a spaghetti western standoff.

The AI adapts completely — combat, dialogue, characters, atmosphere — to fit whatever world you're playing in.

• High Fantasy — Enchanted forests, dragon lairs, ancient prophecies

• Science Fiction — Space stations, alien politics, rogue AIs

• Contemporary Noir — Rain-slicked streets, corrupt officials, moral grey zones

• Gothic Horror — Decaying mansions, eldritch rituals, sanity as a resource

• Frontier Western — Dusty saloons, noon standoffs, lawless territories

• Post-Apocalyptic — Ruined cities, scarce water, desperate factions

• ...and anything you can imagine

Conversations That Actually Matter

Every NPC has memory, mood, and personality. Walk into a tavern and the three people inside will react to you — and to each other — based on who you are and what you've done.

The approaches available to you are defined by the world you're playing in, and the AI tailors its proposals to your specific character — your history, your personality, your reputation with this person, right now.

Escalate a conversation the wrong way and watch the tension rise — from polite exchange to sharp words to weapons drawn. De-escalate cleverly and the crisis dissolves. The engine tracks every state.

Combat That Thinks

Every fight is a story. The engine resolves outcomes through real mechanics — your stats, your equipment, conditions on both sides, the environment around you — before the AI narrates a single blow.

• See your success odds before committing to an action

• Use the environment: kick over oil barrels, collapse scaffolding, swing from chandeliers

• Chain actions — a successful feint opens devastating follow-ups

• Conditions change everything: Burning, Blinded, Off-Balance, and more

• Not every conflict needs to be a fight — conflicts escalate through stages, and clever players find other ways

Build Any World You Can Imagine

The World Editor is a full creative suite. Whether you want to automate everything, collaborate with AI, or write your own prose and lock it in forever — it's all possible.

Full Automation

Describe a world in a sentence. The AI builds it: areas, locations, NPCs, lore, item tables, encounter groups, connection maps. A playable world from a single idea, ready in minutes.

AI-Assisted Authoring

The AI drafts; you refine. Generate a location description, then rewrite it in your own voice. Mix your prose with AI-generated content, field by field, character by character.

Author's Canon

Write your prose. Lock it. From that moment on, players see your exact words — no AI paraphrasing, no runtime alterations. The scroll they find in the dungeon? Your sentences. The innkeeper's speech? Your voice.

• Visual world map — drag, connect, and navigate your world as a living network graph

• Upload books, PDFs, or documents — the AI extracts lore and seeds your world from them

• Natural language commands — "Make Elara more suspicious" or "Add a secret tunnel beneath the library"

• Per-field AI control — lock what you love, generate what you need

• Full-screen Focus Writing Mode — distraction-free prose editor with Dark, Light, and Terminal themes

Your Adventure Becomes a Novel

That tense negotiation in the tavern. The desperate last stand. The betrayal you didn't see coming. Synthasia remembers all of it — and transforms your gameplay into literary chapters you can read, share, and keep.

The AI analyzes your sessions to find the dramatic arcs, writes them as structured prose, reviews its own work for consistency, and exports a novel you'd actually want to read. Not a chat log — a story.

A World You Can Hear and See

Real-Time Voice Narration

Kokoro TTS runs on your GPU via WebGPU, narrating your story in natural, expressive speech. No cloud, no subscription, no voice data leaving your machine. Just your story, spoken aloud.

AI-Generated Visuals

Every location, every NPC portrait, every key moment rendered by AI art. Multiple providers supported — cloud-based or local via ComfyUI. Characters stay consistent across sessions: same face, same aesthetic, every time.

Bring Your Own AI

Synthasia works with the LLM provider you prefer — or already pay for.

• OpenAI (GPT-4o, o1, and others)

• Anthropic (Claude Sonnet, Opus, Haiku)

• OpenRouter (hundreds of models via one API key)

• Local models via Ollama — fully private, no API key required

Swap providers any time. Your worlds, saves, and stories are yours regardless of which AI is running them.

Back to the Origins

In 1977, Zork proved that words alone can build worlds more vivid than any screen. Synthasia picks up where Zork left off — same magic of pure imagination, same power of text to paint worlds in your mind.

But now, the world talks back. It thinks. It remembers. It surprises you.

The most revolutionary thing in gaming? Going back to where it all began.

Early Access

Synthasia launches in Early Access as a functional, playable game with a growing feature set. The core experience — AI Game Master, World Editor, novel pipeline, voice narration, image generation — is all present. Early Access is how we build the final release: in the open, with the community, one chapter at a time.

Join the Discord to shape what comes next. Learn more and see the game in action at .