Microprose (later Infogames/Hasbro), 1998, 1-5 players, ages 12 and up. This is a very faithful adaptation of the classic Axis & Allies boardgame. You can play any or all of the 5 different powers, leaving the rest to be operated by the A.I. (or other humans if you are running a networked game). There are lots of fun game options you can play around with (turning different rules on or off, changing victory conditions, even changing the basic properties of the different combat units). This game is maddeningly close to being something really great. Unfortunately, it doesn't quite make it. First of all, there are a lot of bugs in the game. And I mean big annoying ones. See how you feel after you spend 3 hours playing a game only to have one of your enemies suddenly be able to purchase all of their military units for 1 IPC each. Nothing like having to deal with the bad guy dropping 150 tanks on his home territory!
And as annoying as the bugs are, it's the A.I. that really disappointed me. It starts out looking like it's really going to provide some serious challenge in a solitaire game, but apparently each power is programmed with a very limited range of strategies and if you do anything to interfere with those strategies the A.I. tends to go into a shell and just sit there waiting for you to come and blast the hell out of it. And if you try playing just one of the countries and hope to get any kind of sensible cooperation from your A.I.-controlled co-power, forget about it. I tried playing the Soviet Union and finally gave up after the U.K. spent all of its turns and resources producing a fleet of 25 submarines instead of invading Germany. This game can be fun in the same mindless sort of way that playing computer solitaire can be fun, but it has too many problems to have much staying power.
There is an add-on/expansion of some kind called "Iron Blitz" which I have not yet tried. Supposedly it has some interesting new scenarious, but it is also highly sought after and so far I've balked at the notion of paying over $100 for a copy. I imagine I'll give in some day, though.
Update: I recently tracked down the original Microprose patch file for Axis and Allies (axis_133.zip) and tried it out. I have to say, it improves the game quite a lot. Most (but not all) of the bugs are gone and the AI is a bit more formidable. I'd say it provides a good solid 4-5 turns of challenging play before you finally beat it into submission. Not too bad. While playing the Germans I actually watched Japan march across North America and conquer the United States. Unfortunately, the AI-controlled Germans and English do still tend to get stuck in a rut once they run out of contested territory in Europe and Asia (just once I'd like to see the Germans build a danged ship after their initial naval allottment has been destroyed and go invade Africa, England or even America).