Is it possible for a player to create an RTSession and join it, and allow other people to join it, without them participating in matchmaking?
Apologies for the late response, you can match players manually by using a pending match, you can read more about this in our guide here.
If you have any further questions please don't hesitate to ask.
Ready to assist further,
Well the case is, that sometimes players can create a game for their friends/guild-mates only to join. There is a link posted into the guild activity chat which when a player taps will have them join it.
The game starts when 4 people have joined.
It seems to me that this would be a lot more appropriate to do as a challenge instead of matchmaking, except there doesn't seem to be any way to do a 'real time' challenge (ie, an RTSession is allocated, all the players can connect to it, and can keep track of disconnections).
So. That is my predicament.