I have noticed (and I have only been playing the game one level below intelligent), that once you have become a superpower the game is pretty much over, even if you have 75% of the map to conquer.
It seems that the AI is only too happy to be your best bud, even when your influence is drowning them and you are gobbling up other races. This MAY keep them out of hot water for a little while, but an alternate strategy would be to quickly downgrade relations with you and quickly upgrade relations with everyone else. This could lead to a more 'United Front' which would still make the game a challenge, even if you are a super power, especially if the AI was clever enough for this Front to all declare war on you at the same time.
I was going to recommend that Alliances not need a Close relationship with someone else in order to promote this behaviour, but I imagine this change would wreck havoc on the AI.
I think one of the problems here, is that the AI generally 'Roleplays' while the player generally does not. What I mean here, is that I have never had a good AI buddy stab me in the back, but I have stabbed AI 'soulmates' frequently. The net result is that AIs become friendly hoping to appease the player, but appeasement is impossible against power hungry emperors like myself. We only understand force ....
Dano
