Google Play Games Services Multiplayer and Backend

Question

I am thinking about using Play Game Services, with turn-based multiplayer, to power my Android game.

I need to save the outcome of any game to my backend (here, Google App Engine) : mainly the winner and the score, for accounting purposes. However, I don't find any mention of a custom server in Play Games docs.

How can I combine GPGS multiplayer with a backend ? More specifically, how can I check if said user is effectively logged in to GPGS ?

Maybe the clients can send this data to the server, but I fear the data can be tampered with. And because it's a 1v1 battle, there is no way to check with other users if the data is correct.

Thanks for any clues.

Answer 1

I have developed a multiplayer game using GPGS and I used the service 'Cloud Save' (now it has been changed to Google Play Games Saved Games service) to store the scores of each player. It is saved for each account, so the data can be loaded/saved from different devices.