[Gameplay] Cityguards (can't move out, but defend)
I think it would improve the gameplay, if there would be real cityguard units in the game. The AI don't need to train them, they just take part in tactical battles when defending cities. They are the local population. The plebs and the nobels and they don't go to war with the sovereign. They just want to defend there homes.
The level and number of units would depend on the warefare tech.
With this option the game for the player would be more challenging.
The difficulty level of the nation could determine the existence and the power of the guards. Or it could be a detached option.
And the AI vs. AI battles? I don't know if there is needed this for the calculation. I think no, because the attacker would fall most of the time.