Orbit Guard

A Wear OS arcade game built around the rotating crown. You defend a reactor core at the centre of the watch face; the crown spins a shield arc around it.

Roughly 25 KB, no dependencies, no Gradle. Build artifacts are git-ignored — build it with build.ps1 (below) or grab a prebuilt APK from Releases.

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Play

Input	Action
Rotate the crown	Spin the shield around the core (the whole game)
Tap	Start / retry
Hold ~0.6 s on the title or game-over screen	Flip crown direction (saved)
Drag on screen	Fallback aiming, for testing off-watch

Rules:

• Red bolts — block them. One that reaches the core costs a hit point.
• Green charges — let them through. They refuel the core (+1 HP, or bonus points at full health). Blocking one breaks your chain.
• Purple splitters — blocking one breaks it into two fragments that re-enter just outside the shield, so you have to swing back across to catch both.

Blocking without mistakes builds a chain multiplier (up to ×9). Speed, spawn rate and a slow angular drift on incoming bolts all ramp with your score. Five hit points; best score and best chain persist.

Crown handling

AXIS_SCROLL from SOURCE_ROTARY_ENCODER is converted to a scroll distance in pixels using the device's own getScaledVerticalScrollFactor() — the same normalisation Wear's scrollable views use — and then to degrees. That keeps the feel consistent across watches with different encoder resolutions, instead of hard-coding a degrees-per-detent constant.

Calibration as shipped: one screen-height of equivalent scrolling = one full 360° revolution of the shield. Tune with ROTARY_SENSITIVITY in GameView.java.

Events are handled in GameView.onGenericMotionEvent, and GameActivity forwards any that no view consumed, since some Wear builds deliver rotary scroll to the activity rather than to the focused view.

Build

No Gradle and no network needed — the app uses nothing beyond the framework android.jar, so it compiles straight through the SDK build tools.

powershell -ExecutionPolicy Bypass -File .\build.ps1

Pipeline: aapt2 compile → aapt2 link → javac → d8 → zip in classes.dex → zipalign → apksigner. Output lands in dist/OrbitGuard.apk.

The script picks up the SDK from ANDROID_HOME (falling back to C:\Android\sdk) and uses build-tools 36.0.0 with platforms/android-36.

Signing

On first run the script generates a throwaway dev signing key at keystore/orbitguard.jks. That directory is git-ignored and is not in this repository — you get your own key the first time you build. It is fine for sideloading and useless for Play Store publishing.

To sign with your own key instead, set any of:

Variable	Default
ORBITGUARD_KEYSTORE	keystore/orbitguard.jks
ORBITGUARD_KEYSTORE_PASS	orbitguard
ORBITGUARD_KEY_ALIAS	orbitguard

Install

adb install -r dist/OrbitGuard.apk

To sideload to a real watch, enable Developer options → ADB debugging → Debug over Wi-Fi on the watch, then adb connect <watch-ip>:5555 first.

Project facts

• Package com.neo207.orbitguard, launcher activity .GameActivity
• minSdk 26, targetSdk 35, declares android.hardware.type.watch and com.google.android.wearable.standalone (runs without a paired phone)
• Zero dependencies — plain Activity + a custom View drawing on a Canvas, driven by Choreographer for vsync-timed frames
• Entities are pooled and paints pre-allocated, so the frame loop does not allocate
• Layout is derived from min(width, height), so it fits round and square watches at any size

Verified on a wearos_large_round emulator (454×454, API 34): installs, launches, plays, scores, ends, and persists a high score, with the crown driving the shield.

Tuning

All in GameView.java:

Constant	Effect
ROTARY_SENSITIVITY	Crown travel per rotation
SHIELD_HALF_SPAN_DEG	Shield width — the main difficulty dial
MAX_HP	Starting hit points
level() / spawn()	Difficulty ramp and projectile mix

Opening in Android Studio

The manifest carries a package= attribute because aapt2 requires one for the manual build. AGP 8+ rejects that attribute, so if you convert this to a Gradle project, remove package="com.neo207.orbitguard" from AndroidManifest.xml and put namespace = "com.neo207.orbitguard" in the module's build.gradle instead.

License

MIT — see LICENSE.