I have not yet bought or played Tomorrow's War, but it's part of the Force on Force series, which appeared in my game club a few months ago and seems pretty popular. I have the core rules, and have played a few games of Force on Force. The mechanism is very simple and easy to learn, moves quickly through the turns, but it also seems fairly realistic.
In the combat system, attackers and defenders both roll, with the defenders getting a few bonuses for armor, fortifications and things like that, and the attacker trying to beat his roll. But here's the catch: The dice used are different depending on the training level of the unit. So, for example, highly trained professionals will use D12 for all their rolls, average troops will use D8 or D10, and poorly trained troops might use D6 or even (in extreme situations) the dreaded D4.
In this game, highly-trained commandos (and presumably space aliens with death rays) will dominate the battlefield. Insurgents will have a very tough time (believe me, I'm speaking from experience
).
One of the features I liked, was that in a firefight, you don't always know if your guys have been hit or not. If hit, they might be dead, wounded, or it might turn out to be nothing at all. You find out after the shooting is finished. I like the uncertainty of that rule.
the scale is not quite skirmish, although each figure = 1 man. You are actually playing as the squad or team leader, and you're moving your men as a unit.