I'm certain the number of turns also comes into play. I dominated the entire galaxy, but killed them slowly. It would make sense that score would favor the aggressor, if your plan works. My current game, first one on challenging/gifted, is taking FOREVER, because the Yor without resistance from me, became 4x anyone's power. Solution, get everyone to declare war on the Yor, and when they surrender, they surrendered to ME because were were Cordial. I was holding my own against the Yor when they were 4x, but now they are only 2x and momentum is on my side. Its time to unplug the toasters
but I expect a low score because of how long it took.