Thanks for the shout out about the vocab. I was playing around with ideas on what to a call a game played simultaneously and interacts with one another, "Tandem Quest" felt the best to me. I had an instance where I DM'd a 12 person game, and I said "Never again." Next time around I convinced one of the players to DM in tandem, and we made up interactions as we went. I wish I had more time to provide the Opposing Dungeon (which is in the works and being created by my partner DM).