SSG's Battlefront Series
For those not familiar with it, Battlefront was an operational level system that had been around for over 10 years. The first games in the series were for the Commodore 64 and Apple II followed by the IBM and then the Mac. The best feature of the Battlefront series is that the user issues action orders (assault, defend, reserve, etc.) to groups of units but does not actually control each unit. While the unwanted actions of individual units can be maddening, I think the system accurately reflects command and control (or lack thereof) in World War II battles. The interface also made large battles easier to manage since the players weren't controlling each unit on a hex by hex basis.
The objective of each game in the series is to obtain the highest number of victory points. This is done by capturing objectives, destroying enemy battalions, while preventing the destruction of your own battalions. In addition you are the commander of all units and all this entails. That means there is the uncertainty of command separation. You truly have little direct control over the location of battalions. Based on your orders, they will position as themselves as best they can. Also, as the commander you are responsible not only for combat but also supply and management of resources. You need to stay aware of unit losses, supply and administrative levels of each regiment and act accordingly.
Combat takes into account a wide array of realistic factors such as the experience of the unit; supply state; administrative level; off-board support allocated; support from other regiments/battalions; combat bonuses; brittleness of a unit. Combat bonuses are probably one of the most important items to consider. Combined arms attacks (i.e. attack by artillery, armor, and infantry) gets a bonus. Off-board support is counted as artillery. This is an important combat bonus to have in this game unless you are attacking a depleted/routed unit. The movement of units is handled by the computer and is based on administrative level; experience level; supply level; leadership level; current orders; small random factor.
As I said, to make the series even more realistic you do not have total control over each unit. During the madness and fog of battle a commander can essentially only hope his orders are followed to the letter. It is entirely appropriate that you can't just slug away at an opponent. It is as much an asset management game as it is a war game. But then, war really does boil down to the logistics of the situation. You need to watch unit fatigue, losses, supply lines and states. You need to give units rest/refit at the proper time. You need to keep HQ's close (but not too close) to the action to support the units. You need to maintain awareness of your supply and not perform unnecessary attacks as these will drain your supply. I also like the fact that just because I order a unit to take Hill A, something (i.e. the enemy) might intervene to divert that unit.
The scenarios range from even to outright hopeless. However, you can experience this from either side and have the computer play the other. If you are willing, you can edit the basic scenario to give is more play balance. The longevity of the series was sustained in that you could create your own scenarios.