Hmm... hm. About the commander, one thing that seems to be universal in these sorts of games is that the player can see from the perspective of all their units. Changing that would make your game unique and fresh in comparison. Which brings to mind a day-night cycle and weathers... hm.
Not quite sure if you misunderstood what I mean by commander (did you take a look at the link?), each unit consists of ~1000 individuals (represented only by a number), by commander I meant that 1 of these individuals per unit, would be "special", in that if he ever dies, there would be some sort of repercussion (most likely a morale hit).
I think what you're talking about is the general, i.e the guy who is leading
all the units. The problem with changing FOV to be based only on the general's view, is you cannot interact with units you can't see. For example, consider some cavalry hiding in the woods. In game terms, "hiding" would be represented by not drawing that unit on the screen. However, you'd only make the unit disappear for the enemy, not for yourself. If you did the latter, how would you give any additional orders?
In real life, orders were given in several different ways: flags, drums, trumpets, messengers etc, so that the above problem is avoided (or at least reduced). Furthermore, generals had to keep track of where their units were, using their memory, communication networks, maps, detailed plans etc. on a constant basis. While I could simulate this by keeping hidden units invisible on the map (by not drawing them, but still allowing them to take orders) it becomes more of an annoyance than a feature, where you are flicking the mouse across the screen trying to find your invisible unit, rather than strategizing.
This could work, if the movement system was overhauled into a coordinate system, where the player must enter the coordinates he wants his troops to move to (maybe using waypoints for the above case). But since the game is turn based, this seems overly tedious and I prefer the simple mouse-based GUI that I currently have.
However, there
is another way to implement what you're suggesting, and its something I've planned to add: we simply decrease the probability of being able to control a unit at the start of the turn, varying this probability relative to the unit's distance from the general and to the terrain it stands on (hiding in forests, on top of a hill). This feature is already half-in in the form of morale; morale works by picking a random number from 1-100 and if that number is greater than the unit's current morale, that unit cannot do anything this turn. Right now its a little wonky because the probability is linear (ideally it should be logarithmic) but it is not hard to generalize this, and have other factors influence it.
I've been on the fence about this particular feature (limiting control based on general's FOV) but I think, as you stated, it would make the game a little more interesting, fresh and new.