Yesterday I finished playing a single player game in a free for all with 9 AI opponents. It was fun, but there was something not quite right about it....
For almost the whole game I was at peace and trading with 2 other AI players. At the end, I had completely taken 3 star systems, one of my allies had taken one small system, and the three of us shared on system (I presume the one they had started in. I got rid of their less-than-friendly neighbors.)
Anyway, to 'win' the game I had to turn on my allies which made me feel.... evil. I didn't like it.
Not a bug. Not even a complaint, I guess. But maybe an option to call it a win for you if everyone who is hostile to you is pacified.