title: Integrating Google Turn-Based Multiplayer with Google App Engine
body: <p>My existing Android (Java) game pits the player against up to eight AI opponents.  I've now decided to implement an asynchronous online turn-based multiplayer mode.  As I currently support leaderboards and achievements through Google Play Game Services I was hoping to use their turn-based multiplayer API but this has proved far from ideal due to the following restrictions within that API -</p>
  
  <ul>
  <li>Every player has to remain in the app for the duration of the game</li>
  <li>Only one multiplayer game can be played at once</li>
  </ul>
  
  <p>My game is of the type where you might play a turn and then close the game down until a notification comes in to say that it's your turn again.  Also, for an eight player game it's unlikely that all eight instances are going to remain running throughout the duration of an entire game.  It's also likely that a player will want to participate in a number of different games at once.  (Although the game is nothing like Draw Something, their multiplayer model is similar to the type that I need).</p>
  
  <p>Having dismissed the possibility of using the turn-based API, I've been looking into other possibilities and have come across App Engine.  Unfortunately 99% of my developer experience is with client-side coding so some of these questions may seem naive...</p>
  
  <ol>
  <li><p>Is it possible to integrate Google Play Game Services with Google
  App Engine?  I would ideally like to keep everything tied to each
  players' Google account seeing as I'm already using Google Play Game
  Services for achievements and leaderboards.</p></li>
  <li><p>Is App Engine suitable for allowing multiple instances of
  asynchronous turn-based games?</p></li>
  <li><p>Will I be able to use parts of the multiplayer API such as the lobby
  system or will it all need to be written from scratch?</p></li>
  <li><p>How much of a learning curve will be involved with setting up the
  backend system?  What resources will I need?</p></li>
  </ol>
  
  <p>Any advice on the above will be very gratefully received.</p>