Hosting a Server

Run Open Historia on your own machine, play offline, or reach it from your phone on the same network.

The desktop app already runs a local server — that is how it works. This page is about running that server deliberately: to play entirely offline, to reach your campaign from another device, or to keep everything on hardware you control.

There is no multiplayer. Hosting lets you reach your game from another device. It does not let two people play the same campaign. If you connect from your phone and your laptop at once, you are two windows onto one single-player game, and you will fight each other for it.

What you get

• Fully offline play. After install, nothing needs the internet — map, rendering, scenarios, editor and interface are all local. Only the AI needs a connection, and not even that if you run a local model.
• Your data on your disk. Saves and scenarios are files you can back up.
• Play from the sofa. Start a campaign on your PC, carry on from a tablet.

Running it

If you installed the desktop app, you are already running it. To run the server on its own from a source checkout:

git clone https://github.com/Open-Historia/open-historia.git
cd open-historia
npm ci
node scripts/fetch-map-assets.mjs
node server/server.js

It listens on port 3000. Open http://localhost:3000.

Node.js ^20.19.0 or >=22.12.0 is required on the server machine. Client devices need only a browser.

Connecting from another device

The server answers only the machine it runs on until you say otherwise. There are two ways to open it up:

• In the game: ☰ → Settings → Advanced → Network → Let other devices connect. It takes effect immediately, without a restart, is remembered, and shows the address to type on the other device.
• From the environment, for a headless box: OH_HOST=0.0.0.0 node server/server.js for every interface, or OH_HOST=192.168.1.9 for one. When OH_HOST is set it wins, and the in-game switch says the environment owns the decision.

Then open the address it gives you — http://192.168.x.x:3000 — from the other device.

Writes from a page served by a different origin are blocked either way, which is what stops a web page you visit from editing your saves. To allow them:

OH_ALLOW_CROSS_ORIGIN=1 node server/server.js

Read this before you open it up

The game's API has no password. There is no login, no token and no permission model.

Once it is open, anyone who can reach port 3000 can read, change and delete your games and scenarios. On a home network behind a router that is generally fine. It is not fine on a shared, public or untrusted network, and it is emphatically not fine exposed directly to the internet. Turn the switch off again when you are done.

Two things soften it: requests from other devices are rate-limited (1,200 a minute by default), and the AI relay — which forwards requests to providers that refuse browser calls — still answers only this machine, so your computer cannot be used as an open proxy by anything on the network. Set OH_ALLOW_REMOTE_RELAY=1 if you do want a device on your network to relay its AI calls through this server.

If you want to reach your game from outside your home, use a private network overlay — Tailscale, ZeroTier or a WireGuard tunnel — rather than forwarding port 3000. Those give you the same access without publishing an unauthenticated API to the world.

If you must expose it, put it behind a reverse proxy such as nginx or Caddy with authentication in front.

Environment variables

Running as a service

Linux — systemd. Create /etc/systemd/system/open-historia.service:

[Unit]
Description=Open Historia Game Server
After=network.target

[Service]
Type=simple
User=your-user
WorkingDirectory=/path/to/open-historia
ExecStart=/usr/bin/node server/server.js
Restart=on-failure
Environment=PORT=3000
Environment=OH_HOST=0.0.0.0

[Install]
WantedBy=multi-user.target

Then sudo systemctl enable --now open-historia. Drop the OH_HOST line if only that machine should reach it — and read the warning above if you keep it.

macOS — a launchd plist in ~/Library/LaunchAgents/.

Windows — Task Scheduler, triggered at logon, running node server/server.js in the project directory.

The map data

The map binaries — roughly 200 MB of vector tiles — are not in the Git repository. They are release assets, fetched by:

node scripts/fetch-map-assets.mjs

Without them the map is blank. The desktop app does this for you on first launch.

Where your files are

Under the data directory: your games, your scenarios, uploaded basemaps and flags, map editor documents, and the manifests that index them. Back up the directory and you have backed up everything.

Do not edit save files by hand while the game is running. Use the cheats panel for changing a campaign — it goes through the same validation the game does.

Privacy

No accounts, and no game data leaves your machine. Your AI provider key is stored locally and sent only to the provider you configured.

Two things do reach the network by default: the browser build's analytics on the website itself, and an anonymous counter that pings when a Community Hub scenario is imported (set OH_IMPORT_COUNTER_URL to an empty value to disable it). Neither carries game data.

Next

• Playing on your phone — the Android app, which needs no server at all.
• Saves and rollback — what is in the data directory.
• Connecting an AI provider — running a model locally too.

Open Historia is under active development on two channels, and this wiki is written by hand — a page can fall behind a release. Last checked against the game on 2026-09-24 · main e62a1c55 · beta 2f48a6c2. If something here does not match what you see in the game, trust the game and say so on Discord.