My original goal was for the AI leaders to act human. But humans are ambiguous, moody and sometimes just plain crazy. This can be interesting when youre dealing with actual, real humans, but I learned the important lesson that when youre simulating one with a computer theres no way to make this fun. Any attempt to do so just turns into random, unproductive noise.
I came to realize that while diplomacy is a unique challenge, its ultimately still just a gameplay system just like any other. Regardless of whether your enjoyment is derived from roleplaying or simply a games core mechanics, if your opponents goals and behavior arent clear then youll have absolutely no idea whats going on or what to do.
In Civ 5, you might have been lifelong allies with a leader, but once you enter the late-game he has no qualms backstabbing you in order to win. With this being the case, whats the point of investing in relationships at all?
By no means should AI leaders be completely predictable. However, they do need a clear rhyme and reason behind their actions. The computer opponents in Civ 5 were completely enslaved to their gameplay situation, and as a result they appeared random and very little of their personalities shone through.
They were all crazy, and in the exact same way. In the months after the game was released I modified their behavior to be more predictable, but it was too late to completely change course. The biggest takeaway from this is that the only thing which matters in a game is the experience inside the players head. It doesnt matter what your intentions are or whats going on under the hood if the end result just isnt fun.