In development ยท building in the open
Worlds that remember.
Vivarium is a long-form AI roleplay and world-simulation app. Step into a living world as a character of your own. The people you meet keep their own schedules, beliefs and grudges. Skip ahead an hour, a day or a week, and the whole world catches up.
The AI controls expression.The application controls reality.
The AI narrates and gives every character a voice, but it never decides what is true. The world's state, the rules and every roll of the dice live in the application. The model only describes what happened.
How a turn works
- 1
You act
Say what your character does, in your own words. Persuade, sneak, bargain, fight, wait.
- 2
The world resolves
The application checks what your character can actually do against stored facts and rolls the outcome before a single word of prose exists.
- 3
The AI narrates
The narrator is told what happened and writes it well. Every character speaks in their own voice. Nothing it writes can overrule the result.
What that gets you
Consequences that stick
Every change to the world is recorded and can be traced back, so a story never quietly rewrites itself and a promise made in chapter one still binds in chapter twenty.
Characters with lives
Non-player characters keep schedules, hold beliefs, learn things and form opinions of you. Skip a day and they have been somewhere, done something and maybe changed their minds.
Time is yours to spend
Rest an hour, wait out the night, or skip a week. When you do, the world moves with it: who travelled, what changed, and what people now say about the last time you were there.
Honest dice
Outcomes resolve against your character's real numbers. You see bands and names, never a hidden roll fudged by the narrator.
Your own worlds
Author places, people, items and lore, then play in them or share them. A world you publish is copied for each player and never changes under them.
Your own model keys
Bring the AI provider you already pay for. Keys are encrypted the moment they are stored and are never shown again, to anyone.
From the devblog
All postsVivarium is built in the open, one milestone at a time. Subscribe with RSS to get new posts as they land.