I always play with 7 civs, because I assumed it is the hardest setting. However, now that I have put some thought into it, I'm not so sure anymore. At 7 civs, I can quickly take over one or two enemy civs, and immediately become the largest & strongest civ, which then gives me more and more momentum towards winning the game, whether by conquest or by sending a spaceship to Alpha Centauri. What is the general opinion on this? What number of civs is hardest to play?