Milton Bradley, 1986, 2-4 players, ages 12 and up. I'm a big fan of these Milton Bradley "Gamemaster Series" games from the 1980s (Axis & Allies, Shogun, et al). Fortress America is another fun game to play, although it does take time to come up with workable strategies (on both sides). The playing pieces are pretty nice. Not top of the line, but better than the boring cardboard cutouts you get with the typical Avalon Hill style war game. The rules are well written and easily referenced. You'll spend a while reading them before you get started, but they're written such that you can follow along, get set up and start playing turns while still reading the rules (always nice). Games last a good long time, about 3-5 hours. The basic premise is that the United States has been invaded by China in the West, the Soviet Union in the East and Central America (!) in the South. One player plays America and one player plays each of the invaders (or a combination thereof if you have less than 4 players). Ostensibly it takes place in the "not too distant future" as you play with "hovertanks" and whatnot (as opposed to "non-hovering tanks" I guess), but for all practical purposes it's pretty straight-forward strategic war gaming that could be based anytime in the modern era. The goal of the invaders is to take (and hold for one turn) 18 American cities. America simply needs to wipe out all the invaders.
At first, it will look like the invaders will win the game in a cakewalk. The invaders outnumber the American units and generate reinforcements at a much quicker pace. I played the U.S. and really didn't have any clue as to what strategy to employ at first. The way the invaders rolled over my coastal cities, I thought I was going to get my ass kicked but good. However, after a few turns it became clear to me that what the U.S. needs do is stall the game long enough to run the enemy out of reinforcements and get stretched too thin. Each of the invaders gets 60 units total, and once they run out, that's it, they're stuck with what they have left on the board. America, on the other hand, gets an infinite supply of reinforcements that can pop up anyplace on the board. America also gets the advantage of laser towers, allowing it to take out enemy units anyplace on the board (generally from the safety of the midwest). If you survive past the high water mark of the invaders, you can start raising hell with them by popping up behind enemy lines, taking lightly defended cities and cutting off their supply routes. The game seems really well balanced as the invaders seem to run out of steam right about the time that they're knocking at the doors of that 18th city.
The first time we played we got several critical rules wrong and completely screwed up the game :-) The next time we got things right and I played the American player and lost (by a hair), but I did learn some important lessons for next time- I tried falling back from my coastal cities right away to save (and concentrate elsewhere) military units. This hurt me by not slowing the enemy down enough. Had I made them fight on the coast a little bit, it probably would've bought me another turn or two at the end of the game (all I would've needed to win). Next, I kept most of my mechanized units out of harm's way at the beginning- another bad move. While they could've been fighting (and dying) to delay the enemy, they would've then also been available to pop up as partisans. I missed putting at least 10 mechanized partisan units into play because I didn't have enough killed units available in the tray. Finally, I found out that you really need to decide which 13 cities you're going to try to hold on to. There are 12 cities concentrated in the midwest that are fairly obvious, but it's the 13th that makes the difference. It's either going to have to be in the west (Salt Lake City), South (Atlanta or Dallas) or Northeast (New York or Boston). I didn't really settle on a particular 13th city and wound up scrambling to pick one late in the game. Not a good strategy.
Incidentally, since 9/11 this game has enjoyed a considerable resurgance in popularity, particularly the first edition with the Saddam look-alike on the cover (this was removed from subsequent editions, not sure why. Was Milton Bradley worried about upsetting Saddam??) Expect to pay as much as $100 or more for a complete copy in nice condition.