1. These minor civs would NOT include the same number of units or bonus' that the playable civs get. The whole point of having them is so that there is a more realistic and fun 'feel' to the Conquer the Galaxy campaign. This was basically one of my gripes in terms of RoN in that the 'barbarians' you took uncliamed lands from were exactly the same as each other.
2. To realistically portray the Star Wars universe, to provide motives for attacking different planets, and to reward those players who are more aggressive in terms of expansion. There is no doubt that a player who controls most of the map is the most powerful, but that doesnt mean they are undefeatable either. This can also work well in Empire vs Rebels senario's.
3. Read the first two points.
BTW thought i might just add that not every planet would have a minor civ. Some would be 'colonies' of other worlds, and also there would be pretty much a single human minor civ to cover worlds like Corellia, Alderaan (if it isnt the Republic homewolrd) etc.
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