Arcana Codex for Owlbear Rodeo

Install the extension once, then invite your players to your Owlbear room. No separate Arcana server or database is needed.

Start here: what Owlbear does

Owlbear is your shared tabletop. Arcana Codex opens as a panel inside it. Everyone sees the same adventure, but each player selects only their own hero. The map and tokens are separate from the cards.

Install using this website

  1. Copy this installation address: .
  2. Sign in to Owlbear Rodeo. Open your profile, find Extensions, click Add Extension, and paste that address.
  3. Open or create your Owlbear room. In the room’s extension menu, enable Arcana Codex.

Run your first multiplayer game

  1. You, the GM: open a scene in your Owlbear room. A scene is the saved tabletop where this adventure lives.
  2. Click the Arcana Codex extension icon, then Start adventure in this scene.
  3. Copy your Owlbear room’s invite link and send it to your friends. Send the room link, not the installation link.
  4. Each player: join that room, open Arcana Codex, and create a hero or import a character save. Select only your own character.
  5. You: switch on GM mode inside Arcana Codex. Open the GM tools, add monsters, and start the encounter.
  6. Players: when it is your turn, tap a card and its target, or enable dragging and drag it. Press End turn when finished.
  7. You: use the GM tools to run enemy turns and award cards, relics, or loot. Players choose their rewards and edit decks between encounters.
  8. Next session, reopen this same Owlbear scene. Export character saves as backups from Hero & decks.

Keep one Owlbear GM connected with Arcana Codex enabled while playing. Closing the card panel is fine; leaving the room stops its GM processing. There is no need to keep a ChatGPT conversation open.

Use your own Hestia website

  1. Download and extract arcana-codex-owlbear.zip on your computer.
  2. In Hestia File Manager, open your domain’s public_html folder. Create a folder called arcana.
  3. Upload the contents of the ZIP into public_html/arcana. Keep the assets folder. The manifest must be directly inside arcana, not another nested folder.
  4. Enable HTTPS for the domain through Hestia’s SSL / Let’s Encrypt settings.
  5. Your installation URL is https://tarotcodex.duckdns.org/arcana/manifest.json. Open it to check that it displays JSON text.
  6. In Owlbear Rodeo, open your profile’s Extensions page, choose the option to add a custom extension, and paste the manifest URL.
  7. Enter your room, enable Arcana Codex in that room’s extensions, and open an Owlbear scene.
  8. As an Owlbear GM, click the Arcana Codex icon and choose Start adventure in this scene. Players open the same extension in the same scene and create or import their own heroes.

Solo play

Choose Play solo in the extension to play without a GM or a shared scene. Create one hero, then choose a route through 12 floors. Enemies act automatically. Battles grant card choices, elites grant relics, and camps offer healing or one upgrade. The final floor is a boss. Your run saves on this browser; export your hero before clearing browser data or replacing the run. Cards such as Strike and Guard can now be earned as additional owned copies through rewards.

Dragging cards

In Hero & decks, drag a card onto another deck slot to reorder or replace it. Drop onto Add card to expand a deck, or onto Collection to unequip it. A full card follows your mouse or finger. Reward, catalog, and pile cards can be picked up visually; use their choice buttons to claim rewards, and pile cards cannot be played directly. Scroll from the gaps between cards on a phone, or hold a dragged card near the top or bottom edge to scroll.

Playing

Tap a card, then tap an enemy to attack. For other cards, tap the Play button underneath your hand. Dragging is off by default; turn on Enable dragging to use it. A copy of the card follows the mouse or finger. Dragging remains within the extension panel, not onto Owlbear map tokens.

The same rules apply in both input modes: Energy, resonance, draw, discard, exhaust, initiative and enemy targets are still tracked. GM mode inside the card table follows the honor system. At least one actual Owlbear GM must stay connected with the extension enabled to process actions, even if the panel is closed.

Saving and moving adventures

Adventure state is saved in Owlbear scene metadata. Reopen that scene to resume. A different scene starts a separate adventure. Export each character using Hero & decks before moving to a new scene, and back up the Owlbear scene for the complete battle state. Existing website rooms do not automatically migrate; use character exports.

Portrait uploads are resized to small WebP images and stored with the scene. Exports include those resized portraits. Keep the originals on your computer.

Editing

The separate source ZIP includes owlbear/, the interface in app/, and rules in lib/. Install the project dependencies, then run pnpm build:owlbear. Upload the generated files from public/owlbear/ to your web folder.

This is an independent Arcana Codex extension, not an official Riftbreakers product. The extension uses Owlbear’s SDK. It has no ChatGPT API, database or account dependency when served from your own website.