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Show HN: AI-town, run your own custom AI world SIM with JavaScript

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Screen Shot 2023-08-14 at 10 01 00 AM

AI Town is a virtual town where AI characters live, chat and socialize.

This project is a deployable starter kit for easily building and customizing your own version of AI town. Inspired by the research paper Generative Agents: Interactive Simulacra of Human Behavior.

The primary goal of this project, beyond just being a lot of fun to work on, is to provided a platform with a strong foundation that is meant to be extended. The back-end engine natively supports shared global state, transactions, and a journal of all events so should be suitable for everything from a simple project to play around with to a scalable, multi-player game. A secondary goal is to make a JS/TS framework available as most simulators in this space (including the original paper above) are written in Python.




Clone repo and Install packages

git clone
cd AI-town
npm install
npm run dev

npm run dev will fail asking for environment variables.
Enter them in the environment variables on your Convex dashboard to proceed.
You can get there via npx convex dashboard or
See below on how to get the various environnment variables.

a. Set up Clerk

  • Go to and click on “Add Application”
  • Name your application and select the sign-in providers you would like to offer users
  • Create Application

  • Go to JWT Templates and create a new Convex Template.
  • Copy the JWKS endpoint URL for use below.

b. OpenAI API key

Visit to get your OpenAI API key if you’re using OpenAI for your language model.

c. Pinecone API keys

  • Create a Pinecone index by visiting and click on “Create Index”
  • Give it an index name (this will be the environment variable PINECONE_INDEX_NAME)
  • Fill in Dimension as 1536
  • Once the index is successfully created, click on “API Keys” on the left side nav and create an API key: copy “Environment” value to PINECONE_ENVIRONMENT variable, and “Value” to PINECONE_API_KEY

d. Add secrets to the convex dashboard

Go to “settings” and add the following environment varables. CLERK_ISSUER_URL should be the URL from the JWKS endpoint.

OPENAI_API_KEY  sk-*******
CLERK_ISSUER_URL  https://****

Run the code

To run both the front and and back end:

You can now visit http://localhost:[PORT_NUMBER]

If you’d rather run the frontend in a separate terminal from Convex (which syncs
your backend functions as they’re saved), you can run these two commands:

npm run dev:frontend
npm run dev:backend

See package.json for details, but dev:backend runs npx convex dev

*Note: The simulation will pause after 5 minutes if the window is idle.
Loading the page will unpause it. If you want to run the world without the
browser, you can comment-out the heartbeat check in convex/engine.ts

Various commands to run / test / debug

To add a new world, seed it, and start it running

Note: you can add --no-push to run these commands without first syncing
the functions. If you already have npm run dev running, this will be faster.
If you remove it, it’ll push up the latest version of code before running the

npx convex run init:reset

To go one iteration at a time, you can create a world with

“,”noSchedule”:true}'” dir=”auto”>

npx convex run --no-push init:resetFrozen

# for each iteration
npx convex run --no-push engine:tick '{"worldId":"","noSchedule":true}'

To freeze the back end, in case of too much activity

npx convex run --no-push engine:freezeAll

# when ready to rerun (defaults to latest world)
npx convex run --no-push engine:unfreeze

To clear all databases

Many options:

  • Go to the dashboard npx convex dashboard and clear tables from there.
  • Adjust the variables in crons.ts to automatically clear
    up space from old journal and memory entries.
  • Run npx convex run --no-push testing:debugClearAll to wipe all the tables.
  • As a fallback, if things are stuck, you can check out the origin/reset-town
    git branch. Doing npm run dev from there will clear your schema, stop your
    functions, and allow you to delete your tables in the dashboard.

To delete all vectors from the Pinecone index, you can run:

npx convex run --no-push lib/pinecone:deleteAllVectors

NOTE: If you share this index between dev & prod, or between projects,
it will wipe them all out. You generally don’t need to be deleting vectors from
Pinecone, as each query is indexed on the userId, which is unique between worlds
and backend instances.

To Snoop on messages

Run the following in a side terminal

npx convex run testing:listMessages --no-push --watch

Or to watch one player’s state:

npx convex run testing:latestPlayer --no-push --watch

See more functions in testing.ts.

Deploy the app

Deploy to

  • Register an account on and then install flyctl

  • If you are using Github Codespaces: You will need to install flyctl and authenticate from your codespaces cli by running fly auth login.

  • Run npx convex deploy to deploy your dev environment to prod environment. Make sure you copy over all secrets to Convex’s prod environment

  • Run fly launch under project root. This will generate a fly.toml that includes all the configurations you will need

  • Modify generated fly.toml to include NEXT_PUBLIC_* during build time for NextJS to access client side.

  • Modify’s generated Dockerfile to include new ENV variables right above RUN npm run build


# Build application
RUN npm run build
  • Run fly deploy --ha=false to deploy the app. The –ha flag makes sure fly only spins up one instance, which is included in the free plan.
  • Run fly scale memory 512 to scale up the fly vm memory for this app.
  • Create a new file locally and fill in all the production-environment secrets. Remember to update NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY and CLERK_SECRET_KEY by copying secrets from Clerk’s production instance –cat | fly secrets import to upload secrets. Also remember to update CONVEX_DEPLOYMENT and NEXT_PUBLIC_CONVEX_URL.

Customize your own simulation

NOTE: every time you change character data, you should re-run npx convex run testing:debugClearAll --no-push and then npm run dev to re-upload everything to Convex. This is because character data is sent to Convex on the initial load. However, beware that npx convex run testing:debugClearAll --no-push WILL wipe all of your data, including your vector store.

  1. Create your own characters and strories: All characters and stories, as well as their spirtesheet references are stored in data.ts. You can start by changing character descriptions.
  2. Updating spritesheets: in data.ts, you will see this code:

    name: 'f1',
    textureUrl: '/assets/32x32folk.png',
    spritesheetData: f1SpritesheetData,
    speed: 0.1,

You should find a sprite sheet for your character, and define sprite motion / assets in the corresponding file (in the above example, f1SpritesheetData was defined in f1.ts)

  1. Update the background (environment): convex/maps/firstmap.ts is where the map gets loaded. The easiest way to export a tilemap is by using Tiled — Tiled export tilemaps as a CSV and you can convert CSV to a 2d array accepted by firstmap.ts


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