Hello there everybody..
well thinking about how my opponent should act, this comes into my mind:
we will fight against Romans, right? So... The AI should be as close as possible to a Romans habit.
Now Im no Romans specialist, but I still remember some (basic) stuff from school.
Romans were VERY organized and had magnificent leaders. When I am not wrong - a weakpoint was their unability to act very fast and spontaneaously. Right? So a "long", but effective build up of army could be considerable.
As programming such a massive weakpoint would probably end up in a very boring game - Romans did something against it:
The ability and trust of the dictators appointing regional leaders is another thing, which could be awesome. Because these leaders could differ from each other a lot. Starting from "killing their own units, because they are weak" to "anxious leaders with luck" and ending with "Rebels in their own system (heading for the throne)". Their weakpoint "slow" could be balanced by a young regional leader, who tries to impress everybody and goes out for a quick hunt (sometimes too quick probably...).
JB wrote the opponent should be able to remember the past. Means "Learn" basically. I totally agree with this and would find it astonishing to read a message pointing out what i did earlier. Example for a narcisstic, cocky/jaunty regional leader: "My merchant-spys on your market/streets just reported me you save ressources/build archer army/big army/whatever... I will have an eye on you." Then later: "I assume you saved enough now and you built your second barrack already. Come over NOW!!" (He prepared a better defense already.. etc.)
Or when I attacked him with several small troops in winter weakening him, he will (dependig on his character) change his defense for next winter or strike back ridicously, because he got angry of my teasing.
Learning can as well simply be to remember whether I used more riders or archers at my last attack and adjusting his army to his observations at his next strike.
All this would keep my head busy during playing and it is not just gathering ressources, defending a little, building up a huge army - strike once. win.
Jon.. Sorry, if I drifted off - Im no programmer and never set up an AI, so Im just writing what comes into my mind and what I would consider as "WOW! Awesome reaction!". As well I dont know yet how exactly the gameplay will be - so maybe excuse suggestions, which are simply impossible to implement.