Android

Not built on the authors' machine. npm run android (prebuild, Gradle, an emulator or a phone) was never run for this page. What was run: npx expo config (valid, the react-native-webgpu plugin resolves) and npx expo prebuild --no-install --clean in a throwaway copy of the template, which succeeded and gave the values below. It is not known from our own runs whether the app launches, whether WebGPU draws on an emulator, or how fast it runs. The steps are Expo's standard ones, checked against Expo SDK 58's docs and the template's config.

On Android your game is an ordinary Expo app: expo run:android generates the native project, builds it with Gradle, installs it and loads the game's JavaScript from Metro. The engine needs nothing from the Moonspell app to run there (What is and is not open).

Prerequisites

Android Studio with the Android SDK, and an emulator or a phone with USB debugging on.
Java (a JDK). expo run:android needs Android Studio and Java installed and configured.
Node and npm, and a real npm install in the game's folder.

Run it

npm install
npm run android

npm run android is expo run:android. The first run generates android/ (Expo's prebuild), compiles a debug build, installs it on an emulator or a connected phone and starts Metro. Later runs skip prebuild while android/ exists. Arguments after -- go to expo run:android:

npm run android -- --device

--device lets you pick a connected phone or an emulator.

The template does not include expo-dev-client, so this is a plain debug build that loads from Metro, without the development launcher screen.

What `app.json` needs

The Android part of the template's app.json:

{
  "expo": {
    "orientation": "portrait",
    "android": { "package": "com.rofi.crescentmoon.game" },
    "plugins": ["react-native-webgpu"]
  }
}

Key	Why
`plugins: ["react-native-webgpu"]`	Required on Android. react-native-webgpu's native code needs API level 26 (`androidMinSdkVersion` in its `package.json`), and its `build.gradle` does not go lower for an app with a lower `minSdkVersion`, so such an app fails with a manifest-merger error. Expo's default is 24. The config plugin raises the app's `minSdkVersion` to 26
`android.package`	Change `com.rofi.crescentmoon.game` to an id of your own. It becomes the `namespace` and `applicationId`
`orientation: "portrait"`	Becomes `screenOrientation="portrait"` on the activity

What the prebuild check generated:

Setting	Value
`android.minSdkVersion`	26 (Android 8.0)
`newArchEnabled`	`true`
`hermesEnabled`	`true`
`namespace`, `applicationId`	`com.rofi.crescentmoon.game`
`screenOrientation`	`portrait`

The template sets no scheme, so your build opens no deep links. If you add one, useLaunchRoomId() reads ?room=CODE from the link through React Native's Linking (Net). Not tested.

Emulators and phones

On Android, react-native-webgpu runs Dawn on Vulkan. Its docs warn that Android emulators may fall back to a software adapter: slow, and some features may be missing. Test performance on a real phone.

Release builds

At a pointer level only; none of this was run for the engine:

Locally: npx expo run:android --variant release makes a release build, unsigned. Signing it for the Play Store is covered by Expo: local app production.
In the cloud: EAS Build (eas build --platform android), which handles the keystore (Expo: EAS Build). Expo's development-build profiles expect expo-dev-client, which the template does not include.

Different from the Moonspell app

	Inside the Moonspell app	Your Expo build
How the game loads	The app loads the game's Android export into its own runtime	Your app is the game; Metro serves it in development
Exit button	Back to the app's games	`exitToShell()` does nothing; the template's `App.tsx` unmounts the game and shows its "Play" button
Paused off screen	Yes, while the app's feed keeps the game loaded but not shown	Never: the game is always active
`getLaunchUrl()`, `getShareUrl()`, `roomInviteUrl()`	The app passes the links in	`null`
The app's feed and share links	Yes	No
Game backend	The game's own Worker	`GAME_BACKEND_URL` is `null` in the template: leaderboards, presence and rooms stay on this device until you deploy the backend and set it

Icons on Android draw the Material Symbol twin of each SF Symbol, and Skia text uses the sans-serif family where the engine names a system font. These and the other differences are on Platform differences.

Prerequisites​

Run it​

What app.json needs​

Emulators and phones​

Release builds​

Different from the Moonspell app​

See also​