Good news - the app should now work offline!
If you're out of service and still want to keep track of your health tasks, you can now use the app offline. Just open the app to report your tasks and, if you're having issues reporting your tasks, turn on Flight Mode on your device to ensure offline mode works properly. While you won't be able to play a game, you can always report your tasks so you have a clear record of your task completion.
Please remember: if offline mode doesn't seem to be working, turn on Flight Mode on your device and re open the app.