@endel Now I get it! Thanks so much for the help. I have enough to get started on my project.
Just curious though, why isn't an explicit create call supported? I see it being useful in scenarios where users can create their own game and share it with friends. The rooms can't really be locked when the game starts as the players might change devices during the course of the game. When there are many existing rooms, the creation of new rooms might become expensive. Is it a security concern for the clients to be able to create the rooms, or just not a common scenario?