Wearable games run directly on the wearable device, giving the developer access to low-level hardware such as sensors, activities, services, and more, right on the wearable. A companion handheld game that contains the wearable app is also required when the developer wants to publish to the Google Play Store. Wearables don't support the Google Play Store, so users download the companion handheld game, which automatically pushes the wearable game to the wearable. The handheld game is also useful for doing heavy processing, network actions, or other work and sending the results to the wearable.
To develop games on Android wearables, there are some technical steps to be followed. This is not general Android game development:
The Android SDK tool has to be updated to version 23.0 or higher
The Android platform support within the SDK has to be updated with Android 4.4.2 (API 20) or higher
An Android wearable device or emulator is required for development