BlogNomic: The First Dynasty of Desertfrog

Append the following text to the rule “Calvinball”, if such a rule exists:

Each Child and each Imaginary Friend is on a Team, tracked on the Wiki page called “Calvinball Teams.” Any Child or Imaginary Friend is a Teammate of another Child or Imaginary Friend if they are on the same team. If a Child joins the game or a Imaginary Friend is created, they are assigned to the team with the fewest members, or, in case of a tie, to a random team among those tied for the fewest members.

Of the 13 active Children and Imaginary Friends, randomly assign 7 of them to the Red Team and the rest to the Blue Team.