GUO exports as an ARM64 debug APK for an Android device (the build's floor is Android 7.0, ADR-0017; only Android 13 has been run), without the NDK. The export uses Godot's Gradle build: run.py installs the pinned source template, and the first export needs access to Maven. Source of truth: ADR-0017 (Accepted) and tools\android\README.md, whose run table records what actually ran on a device. The first device run is commit "Android: first run on a device"; everything below has been exercised on one handheld with two screens, so a second device is the next real test.

launchers\android\doctor.bat     REM what is missing, and the fix for each
launchers\android\export.bat     REM a debug APK, headless, into build\android
launchers\android\install.bat    REM adb install onto the attached device
launchers\android\run.bat        REM start it and stream its logcat
launchers\android\smoke.bat      REM export, install, run, wait for the login gump, pull a screenshot and a log
launchers\android\dual_probe.bat REM the second-screen probe, see Dual Screen
launchers\android\portrait_probe.bat REM the portrait spike: turns the screen, photographs each state
launchers\android\device_manager.bat REM the Device Test Manager: device profiles, emulator, screenshots

Underneath: python tools\android\run.py <doctor|templates|keystore|release-keystore|settings|preset|export|install|run|logcat|push|push-stage|smoke|avd|dual_probe|portrait_probe|displays>.

With no data on the device, the first-run screen's Choose folder opens the system folder picker and copies the folder into the app's own files; see tools\android\README.md.

Godot reads the SDK, the JDK and the keystore from its editor settings file and nowhere else (not ANDROID_HOME, not JAVA_HOME), so run.py settings writes the values from config.bat into %APPDATA%\Godot\editor_settings-4.7.tres (a .bak is kept), and export does so before every export. The export preset is rendered from tools\android\export_presets.template.cfg into the gitignored godot\GUO\export_presets.cfg, which carries the keystore path and password; that is why the preset is never committed. The preset excludes addons/guo_editor/* so the editor add-on's sources are not packed.

export.bat --release makes build\android\GUO-release.apk, signed with your own key: UO_ANDROID_RELEASE_KEYSTORE, _USER and _PASSWORD, set in config.local.bat or the environment, never in the repository. The keystore must live outside the checkout. python tools\android\run.py release-keystore makes one and doctor.bat --release checks it. The release workflow builds one on a tag when the repository has the matching secrets. Details, and why the key never reaches the preset file: tools/android/README.md, "A release APK, signed with your key".

The UO install is never inside the APK. run.py push copies it to the app's external files folder, UO_ANDROID_CLIENT_DATA (/sdcard/Android/data/<package>/files/uo), and the export bakes --play --client-data <that path> into the APK's command_line/extra_args, so the app starts straight into the login screen. Exports are silent unless --sound is in the baked arguments.

run.py run --args "--host <address of the PC running the shard>" points the device at a shard on your LAN. The shard must listen on an address the phone can reach, not only loopback; see Dev Shard.

Recorded in ADR-0017 and the first-run commit, in case you hit them elsewhere:

• project.godot sets import_etc2_astc; the export refuses without it.
• No console colour in the logger on Android (PlatformNotSupportedException).
• Managed zlib on Android: the system libz binding aborts.
• The plugin host is a Windows-only build item; a publish for android-arm64 failed in tools\plugin_host before any GUO code was built. Assistant plugins are not part of the Android build.
• The whole-number screen scale divides the OS scale out, so the client's own integer ScreenScale is used instead of Godot stretch. Pixel art stays unfiltered.
• Immersive mode only survives scene changes in WindowMode.Fullscreen, so a mobile OS keeps that mode through the login and game windows.
• The account field raises the e-mail keyboard and the password field the password keyboard: the two input types an Android IME must not autocorrect in. The IME's check mark arrives as Enter and logs in.

The export is locked to sensor-landscape. Portrait was tried on an Odin 2 Mini (2026-09-28) and turned down on one number:

The world works in portrait, and shows twice as far north and south. The command bar does not: its buttons shrink to 2.3 mm tall, which a thumb cannot hit, and the login screen stays where landscape put it, half off the screen. Both are fixable, so portrait could come back as an option later; the measurements and the probe that took them are in the repository's docs/android_portrait_spike.md and ADR-0017.

launchers\android\smoke.bat exports, installs, launches, waits for the login probe's line on logcat ([GUO] prefix, the same line the web smoke waits for), pulls a screenshot and the log into build\android\. It exits 0 only when the login gump was drawn. smoke.bat --avd guo_phone does the same on GUO's own x86_64 emulator: it boots it headless (only with 10 GB of memory free), installs, waits for the login screen, takes a screenshot and cleans up, touching only the emulator it started. run.py displays lists the device's displays for Dual Screen work.

From ADR-0017 and the README table: export, install, login by touch alone, shard list, character selection, arriving in the world, hold-to-walk, pinch zoom, zoom kept across relaunch, the soft keyboard typing an account letter for letter, and the smoke exiting 0. All on one Android 13 handheld against the dev shard over the LAN.

ADR-0017 still carries a "Written, not run" list from its first pass beside its Accepted status; read the ADR's Validation section for what is actually crossed off. Nothing has been run on a second device, on Android 12 specifically, or on a phone with one screen and no physical controls, so treat those as written, not verified. CI publishes the .NET half of the Android export on every push (.github\workflows\build.yml) but cannot run the engine or export an APK, and says so in the workflow.

The touch layer and the per-platform profile that make a phone playable are on the Mobile UI page.