On-line gaming session and party management

A game hosting service manages game sessions and groups of players. The service creates, starts, and ends a game session. The service also manages the joining and deleting of players and groups of players both prior to and during game play. The service collects, stores, and optionally arbitrates statistics for each player such a game score and relative ranking with other players. The service assigns a group ID to a group of players to allow the group to migrate across game sessions. The game hosting service utilizes session management APIs to nest multiple sessions, thus enabling groups of players to remain intact across multiple sessions.