This plugin doesn't officially supported by Scirra, but still belong to Scirra as a real owner.
What I do is only publish it from (#Mayfly) and did a little change from the plugin id, and so every C2 users can still using the Google Play service.
You need to include this script in your config.xml files.
<plugin name="construct-play-games">
<variable name="APP_ID" value="YOUR_APP_ID_HERE" />
</plugin>