I am currently working on a small strategy game/interactive simulation of historical battles, whose main goal is to give the player – playing as the general of a ancient army – a more realistic amount of control of the soldiers of the said army and more realistically depict the amount of information available to a commander in this time.
One important feature will, of course, be that the player won't be able to maneuver their soldiers around -- especially during battles -- in a way, in which a historical commander in ancient time (by which I primarrily mean circa 400 BCE to about the fall of Rome and primarily in a European/mediteranian context) would not have been able to communicate with his soldiers, making use of, for instance, flag-, trumpet or lantern signals or messengers running to and from the different parts of the army, and also in which the soldiers in a medieval or ancient army would be able to accurately understand or interpret.
I do acknowledge that great differences may exist in this regard between, for instance, the legions of the Romans and the Gauls, but I do still assume (correct me if I am wrong) that the lack of radio -- throughout both antiquity and the medieval period -- still makes it possible to say something about this which in general applies to both ancient and medieval armies.
If the differences between these groups, in this regard, are significant, I would like to know in what way they differ.
Specifically, I am interested in the following:
Is it at all accurate to divide the army into units of specific sizes, which acts may be thought of as one (making any games much easier to make), or would the entire front line melt together to one large mob of people? (and where units such as the Roman cohort thus merely a logistical tool rather than a combat unit).
During a battle and lacking any significant landscape features, How accurately (if at all) would a commander in ancient time be able to tell a group of their soldiers to move a specific distance or turn a specific angle?
During a battle, lacking any significant landscape features, how accurately would these soldiers have the ability to judge said angle or said distance?
would am ancient commander during battle be able to tell a group of his soldiers to attack (or aim for) a specific part of the enemy army? (for instance, tell their archers to aim for the place where someone spotted the enemy commander)
would am ancient commander be able to tell a group of his soldiers to move to notable landscape features (trees, houses, hills etc., and how notable would these features have to be)
How accurately would an ancient commander be able to tell a group of his soldiers to move around relative to their own army (for instance, move units from one flank to the other to prevent encirclement)
I would also very much appreciate references to either historical sources or reliable modern reenactments/experiments.