Host a world on your phone
An Android phone can host a whole campaign for friends anywhere. The app runs a real server inside it (Node, the content pack, the rules engines, the database) and publishes it through a private tunnel with a room code. Nothing on your router changes and no account exists anywhere but on the phone.
Share online
- Enter your world and open a campaign's lobby. Opening the lobby asks the app to share; you can also press Share online in Settings under This device.
- The invite reads "Opening a public address...", then Shared online. The room code shows as the pair
HOSTCODE-TABLECODE; the link and the QR follow the public address. - Send the code, the link, or use the phone's Share sheet. Friends type the code into their app, scan the QR, or open the link in a browser.
- Stop hosting from the notification, or Stop sharing in the lobby or Settings, when the session ends.
The hosting notification
While the world is shared, Android shows a quiet, ongoing notification: Your world is shared, "Friends can join while this stays on", with a Stop hosting action. It is what lets the server keep running when you switch apps or the screen turns off. Swiping the app away from recents stops the share and the server. Playing alone shows no notification.
Background and idle
- Shared: the server keeps running in the background behind the notification for as long as the share lasts.
- Not shared: a world you have left idle goes to sleep after about half a minute, and wakes when you enter it again. Leaving the app while a solo game is open keeps it alive for that grace period.
- Battery saver and aggressive app-killing on some phones (Xiaomi, Huawei, some Samsung modes) can stop a background server despite the notification. Exempt Open Dungeon Master from battery optimisation in the phone's settings if friends report the host dropping.
Friends on the same Wi-Fi
The phone's server listens on the local network as well, so a friend in the room can add it by scanning the server's own QR button (bottom right of every page inside the world) without a tunnel. Sharing online is still the reliable way: without a share, the server stops when the app is in the background.
Voice
A phone-hosted world uses mesh voice: browser to browser through the tunnel's STUN and TURN, with nothing to open. The Dungeon Master's phone relays no audio.
How much phone it takes
The server is light: a campaign with four players and a human Dungeon Master runs on any supported phone. With an OpenAI key the narration happens at OpenAI, so the phone does no model work. Painted battle maps and effects are drawn on each player's own device. Phones with less than 4 GB of memory start with low effects on. Uploads stop only when 256 MB of storage is left.
The sound library is not in the install. An admin at a table sees Download the sound library in the Sound panel: a 76 MB download the phone writes one track at a time, kept across app updates.
Guests and the admin panel
Guests join with a name and a code; there are no passwords on a phone-hosted world, and the app claims the world's admin account for you with a setup code nobody has to type. The world's admin panel (account menu, Admin) holds the AI, picture and speech settings, the sound library, users, usage, reports and campaign plugins; the app manages the address, sign-ups and voice for you.
Backing up
A phone-hosted world's admin panel has no Backup section, and the world lives in the app's private storage. What you can carry off the phone are exports: characters as .odm-character.json, workshops as bundles, and a campaign's story as a reading copy. Uninstalling the app deletes the world with it; a table that must not be lost belongs on a desktop or a server.
