Game Rounds
Each 'game round' is a self-contained map, and hosts a number of players who will compete to win based on the current round's specific win conditions, usually based on the Index of Power.
A player may be present in multiple game rounds simultaneously, and can play as a different nation in each with no bearing on any other match. Resources, provinces, units and so on may not be transferred or carried over to other game rounds, and will only exist in the game round in which they were created or acquired.
Game rounds may be ranked or unranked, public or private, or even have specific rules, resulting in wildly different ways to play.