Tactics is in the game already. When you are choosing hills to defend and softening up stacks and attacking with some units while defending with others, depending on relative strengths and weaknesses, that's tactics, its just tactics trying to take place on a strategy screen. Might as well do it right and take battles to a tactical screen. I'm going to post an example here.
This zip has three files. One is a little mod that allows some maps to be a flat 8 by 8 and the game to continue without settlers or cities. I used it to generate the save game Tactical. This is a forested area 8 tiles on a side with Asoka having two axemen against Isabella with 5. This in turn is what I would like to see happen resulting from the other savegame,Strategic, which uses standard BtS 3.17, when Isabellas Northwesternmost axeman attacks Asokas wounded axeman to the west.
The idea is that when a stack attacks another stack, a break is taken from the regular game and the battle is resolved on an 8 by 8 randomly generated battle map based on the defenders square (or the standard way if the human player so chooses maybe). Every unit becomes one unit per point of combat strength, rounding up. Units that move off the edge are out of the battle, in the adjacent strategic square they moved into (which may lead to another battle). Once all units on the battle screen belong to one player the regular strategic game is returned to. After the battle, unit strengths are adjusted on the main battle screen. The square with the most subunits of a unit gets that unit, at a strength of 1 per subunit present. Subunits in other squares vanish. Unit healing would have to be reformed to be supply based.
Note, this tactical map could vary each time and have tactical ranged attacks even for units like catapults and premodern cannon. It represents a small area chosen somwhere in the tile, a battleground, not the entire tile. Only major features would have to always be represented--the road, the city, the river. And the AI would have to be written to use it.
