Gamers are free to devise their own system for organizing campaigns. ADB published a game reference specifically for various ways/methods of organizing player-generated campaigns. There may be as many "empires" or nations as players, or they may form up into teams, or a single player may be responsible for different races on different fronts (depending on how much recordkeeping and gameplay he is willing to handle). The players will need to devise their system for strategic movement and some sort of economic system for generating resources for starship construction/deployment. They will also need to agree to such things as what timeframe (year) the campaign is set in (this determines what technologies are available for play), how planets are captured, how bases are constructed, etc.