This is where the tile based part mattered for us (and for the AI). Some terrain, obstacles, and tiles simply provide better offensive and defensive bonuses, Controlling them matters.
I am curious if there will be hero spells or if units will have moves that can possibly flush an opposing unit from tiles that provide a bonus. There would have to be a trade of for using the ability or spell.
Or do you consider sending many units to unseat the enemy from the bonus tile a flush?
Obviously I don't know how the system works, but it would be interesting to have the ability to do a bunch of damage, heal OR try to flush a unit from a tile.
What is N? And Controlling the length of a tactical battle
I like the idea of the battles time being limited by something other then just a timer bar. Battle is not pretty, everyone takes some sort of damage or the length of the battle brings the hero to a breaking point where he is willing to sacrifice some troops to end it sooner, rather then loose even more troops in a drawn out fight.
Just tossing out some ideas here:
Attrition
N would be determined on who's territory the battle takes place and attrition.
If you are on your are within your territory boundary you the enemy side would take light damage at the end of a round, after x seconds or after x number of turns.
If you are within an enemies territory your troops would take light damage.
If you are on neutral ground both sides would take minimal damage.
Obviously this could cause some perplexing balancing issues. It does make you move through the battle as each turn reduces your longevity. It also allows for tower/castles to increase or give a bonus to attrition when fighting in your lands.
Warfare Damage (everyone takes damage in war)
This would be similar to attrition but both sides would take minimal to light damage each round, on x turns or on x seconds. This could be combined with attrition or tweaked so one side takes more damage when invading, but damage would be equal when in neutral territory.
This could also be a stat bonus on a Sovereign or Hero that boosts warfare damage or attrition. Or it could be a stat that reduces the ware of war on your troops.
Heroic Rage
Based on how the combat is going or on the hero's traits over time rage builds within the hero of each site. The rage can then be channeled into special abilities or super boost a spell that unleashes devastation on the other site, maybe damaging your own troops, but brings the battle to an end fairly quickly give enough time.
Thresholds
I like this idea. It could run into issues with super powerful units in small numbers. Is there a way to make a simple weighted system based on total combat power, rather then number of units?
Randomization vs. Richness.
How about a few custom designed ones and the other randomly generated to match the environment on the overhead map?
For hand made maps there could be a tile on the overhead map with a name, like "Frogboy's Triumph". If you engage in combat within x spaces of one of these special tiles that specific hand made battle maps would show up.
The hand made maps would then be named and could even have some lore based around them. Maybe a big battle was fought there in the past or there are odd stories about the land, etc.
The rest would be randomly generated to match the surrounding terrain. I enjoy the unpredictably of randomly generated content, it tends to keep the "new" feel longer then lots of hand made maps.
When maps are all hand crafted and just randomly selected I tend to think, "Ohhhh, this one... which has no name but I know it well."
This may also open up the ability for the player to try to take advantage of a custom battle map on the overhead map or avoid it.