I've never been a real fan of the AOE game engine. Still am not. However, the 'campaign' mode of this game is pretty neat 'o'. I'm doing the 'Entire World' campaign right now. The world is divided up into territories, Risk style, but not as many. You start out with one territory and one army. You move your army to a territory and fight for it. But rather than doing a dice roll, you have a RTS skirmish for it. The level of difficulty is determined by how many enemy armies are in the territory and/or surrounding territories, how long the enemy has owned the territory, etc. There are bonus cards you earn through performance and/or defeating your enemies. These cards give you extra starting resources, armies, technologies, etc at the start of the skirmishes. So, if it's going to be a hard battle (the enemy's capitol after they've been their a while) you use these cards to give you help. The AI players have them as well. If an ally has an army in a neighboring territory, they will help defend or attack (depending on what their ally is doing in the battle). The ages are introduced as you play the game. Every couple/few turns, a new age is made available. There's some other stuff too.
So, rather than following some scripted story line that takes you through time with a series of battles, you play this strategy game that would (should) be different every time you play. Other campaign scenrios are 'Cold War' where it's USA vs Russia, where you can attack and defeat, or become more prosperous than the other to win. Haven't done that one. You can do a 'Napoleon' thing where it's Europe in his time. Same thing with Alexander the Great. Anyway, I thought that was cool. No idea if you can do those multi. Would be neat if you could though.