In civ2, MP was fun, but i also found years of replayability in SP. Probably because despite the AI being a push-over, there was a time limit, so it was a challenge to beat a previous score. But in civ3, for some reason it is just not as fun anymore. Already it is hard for me to stay interested for more than 5 turns in the industrial ages, when the AI becomes a push-over (it cant use artillery, so you can roll right over it with arty and inf). So in the industrial age the AI is as helpless as in civ2, but now theres not enough improvements to build, too many units to have to move, and it loses its fun right then. MP would DEFINATELY change that, knowing your up against a competent human that could launch a massive combined-arms attack on your most imortant cities creates a lot more suspense than an AI who is still making longbowmen despite the availability of infantry.