The key element required in all strategy games like this is CHALLENGE. To Challenge the player above and beyond the norm. To make that middle and end game just as challenging as the early game. This by far is what so many games FAIL on when they are created. They make a game and THROW IN an AI. Thus why so many games get such bad raps for being non-challenging and not fun. Even though the fanbois will cream their pants about how much fun it is because they like EASY or just LOOK AT THE PRETTY PICTURES type games.
For me the game is not fun unless the forum is rampant with whiners about how HARD the game is. I remember when Spartan came out by Slitherine the cries of woe that the game was too hard lmao on normal difficulty or easy. Daddy's lil baby of 8 couldn't beat the bad ole units just by throwing everything he had into one glob. lmao.
What I like to see happen is what I've seen happen in a few games. The AI plays against the HUMAN and not so much itself. Centurion Defender of Rome is one of the best empire building strategy arcade games I've ever played. The AI is ruthless on just normal difficulty and will beat the sox's off of you if you don't THINK about what you are doing and how to expand. The Total War series with Medieval Total War and Viking Invasion origional had a feature of REVOLT and REAPPEARANCE of wiped out kingdoms come back with HUGE and STRONG stacks of units for you to deal with. Totally enjoyed that type of mid/endgame play. Shogun II has implemented the AI ALL OUT against the HUMAN in the mid/endgame as well where even your long time allies will turn against you. Again one of the best CHALLENGING games I've played in a long long long time.
So, I would HOPE BRAD reads this and a light goes off in his head about CHALLENGE. Quit worrying about BALANCE for multiplayer EVER. Make a SINGLE player SOLO player game that can beat the sox off of us at at least Hard and higher levels. I'd prefer on normal but the whiners will whine their 8 year olds can't beat it. lol I'm tired of wasting my time playing these ROMPER ROOM games. Great graphics great interface but totally no AI to speak of and certainly not a challenge.