She opens the letter. The room is quiet. You take it from here.

Underfiction is interactive storytelling. Under your direction.

Describe a scene. Choose a character. A frontier language model picks up where you leave off — in literary prose, not chatbot replies. You direct what happens. The engine follows.

— WRITE LIKE YOU READ —

Every response is written as prose. Scene-setting, interior monologue, tension, subtext — the kind of writing you'd actually want to read back. No bullet points, no "As an AI…", no helpful-assistant voice.

— YOU'RE THE DIRECTOR —

Narrate what your character does. Or step outside the story and tell the narrator exactly what you want. Both work. Mix them freely.

• "She opens the letter."
• "Make this scene tense."
• "He's falling apart but trying to hold it together."
• "Skip ahead. It's morning."

Put words in anyone's mouth. Insert inner monologue for any character. Change the weather. Rewrite a beat. The scene bends to you.

— FOUR WORLDS, OR START ANYWHERE —

Pick a starter world and step in:

• Ashworth End — sunlit heather moors and a distant gothic manor.
• Linden Park — a country house surrounded by autumn gardens.
• The Antler & Stone — a warm tavern at the edge of an enchanted forest.
• The Marabou — a deep-space freighter drifting through a nebula.

Or begin from a blank scene. Any setting, any tone, any cast of characters. The world is a spark, not a cage.

— SCENES ARE CHAPTERS —

Each scene has its own arc. When one ends, it's summarized and carried forward so the next one remembers what matters. Long scenes compress older turns automatically to keep costs down. You only pay for the story itself. Summaries and compression are free.

— FRONTIER MODELS, YOUR CHOICE —

Run your scene through Opus, GPT, Grok, or Gemini. Switch mid-scene to see how a different voice handles the beat. Models follow creative direction faithfully — real fiction, real stakes, no refusals.

— PRIVATE BY DESIGN —

Your stories stay on your device unless you enable story sync. Synced stories are encrypted at rest on our servers. Inference runs through a provider that separates your identity from your content at the infrastructure level. No ads. No training on your writing. No data sold.

— CREDITS, NOT SUBSCRIPTIONS —

Frontier models are expensive to run. Credits let us offer them without subscriptions, ads, or compromises on model quality. Buy once, write as much as you like with what you've bought. Nothing recurring.

— TIPS —

Short, specific prompts win. Push the story — the best scenes come from risks. Set emotional targets, not just plot points. Try a different model mid-chapter.

Underfiction is for readers who've wanted to live inside a novel for an hour, and for writers who've bounced off filters and flat prose elsewhere.

Open a scene. See where it goes.