Following on from that, essentially when you load up a transport with X amount of "soldiers" from your planet is taking X amount of citizens of that planet, slapping a gun in their hand and telling them to shoot the citizens of that target planet untill they're all dead.
Like most on here I found it annoying that when invaded you must kill every sentient life-form to win. It's simply not feaseable to arm every single person on your planet and expect them to act like highly trained soldiers. Plus it's such a waste of potentially tax paying people to wipe them out when they could be paying reparations to me for spending the money to buy ships to conquer them!!
Maybe one way to make things a touch more fun would be having a "morale gauge" similar to that found in the "Europa Universalis" which is smack in the middle to begin with and as the battle progresses the morale bar swings one way and the other and once it reaches too low for one side, if there are any soldiers remaining the whole thing collapses. If you could implement somethign like that, if for example there are 4 billion people on the planet, 6 billion invading with VASTLY superior weaponery, the defenders are get pummelled, the morale gauge drops as the people know their hope is lost, so instead of fighting to the end, lay down their arms with say 1.5 billion dead which if maths serves correctly, leaves 2.5 billion tax-paying people ALREADY on the planet, and some soldiers could remain on the planet to enforce the smooth transition of regime change while the rest can bugger off back on the transport to fight somewhere else. The added bonus to that being I don't have to strip my planets of my own citizens each and every time I take one of the enemies...
I could yabber on with even more detail I'm thinking of as I write, but will stop for now and get other people's thoughts.
One question, and this is to people whose knowledge is Universes better than mine in terms of knowledge of programming, would my idea take lots of memory/programming to implement?