there is a heartbeat function, that you can use. Let me see if I can dig up the project. My new job has kept me busy so I haven't had much time of Crowd Gaming lately. I'm thinking that it's probably best to turn this into an open source project so that anyone can keep building on it. I appreciate you taking the time to write to bring my attention back to the project it's always so much easier to motivate spending time on something if you know that people use it
In the controller:
In the main game:
So the controller send a heartbeat every 10s. The main game receives the heartbeat and updates a property on the gamer.
You can then make a check to see if, the lastHeartbeat is less than wallclocktime - 14s (for example) if true, then delete the gamer.