I have spent several hours....days trying to get the google play plugin to work for mobile android without success. When I run my game, there isn't even an attempt to sign-in. I followed these instructions:
"To get around this I've rewritten this plugin to use the native API instead when running in a webview. This should fix the problem, but when creating your app with Google you need to set up your app as a native one not a web one. I will need to update the tutorial for this as there's a number of frustrating pitfalls ( surprise surprise ).
On the plus side some new actions for using native leaderboard and achievement dialogs now exist! They only work in the Android build though.
The fix actually snuck out in the r87 release without a changelog, so it can be tried now.
Create your game through the Google Play Console NOT the Google API Console.
Builds MUST be signed with a key or you will not be able to log in ( can be release or debug builds ).
Specify your app ID as the new "Game ID" property in C3, this is a 12 digit number and can be found in the Google Play Console > Game Services section. If you don't do this, your build will fail.
You need to specify the SHA1 signature of your signing key in the Google Play Console when setting up your game, this needs to be the same key that you will use to sign your game for release. If you don't do this, you will not be able to log in.
Adding new leaderboards and achievements to your game during testing can cause some synchronization issues. Google Play Games Services ( the app that runs on your device ) uses some pretty heavy caching and it can take a long time for new things to appear.
Make sure you list the Google account that you use on your testing device on the Apps testing user list, otherwise you will not be able to log in.
If you miss something on this list, your unlikely to get anything other than a failed log in. I'd like to show more, but google doesn't give you anything to go on really.
Common errors I saw when one of the above wasn't done correctly:
8 - INTERNAL_ERROR An internal error occurred. Retrying should resolve the problem. ( Retrying doesn't really help )
12501 - SIGN_IN_CANCELLED The sign in was cancelled by the user ( This one seems to happen without the sign in screen actually being shown to the user, so the description is also useless )
FATAL_DEVELOPER_ERROR ( Google Play Games Services was crashed by this, and nothing useful was sent to the game )"
Am I doing something wrong or is the mobile service for the google play plugin still faulty?