Vanilla campaigns were played quite a few years prior, probably in russian, probably only text. The rest is Steam release.
After the release of Казаки: Европейские войны, for Age of Empires III any move forward in era, but in the same playstyle looked futile for everyone. It turned out that "everyone" is limited only to local press and local industry, and unlike locals no one gives a slightest crap for any art made outside of yankeestan.
And yet, when Age of Empires III was released long time after Age of Empires II: The Age of Kings it actually did follow that notion. In that time between the second and the third games the landscape has changed. Individual control of every single unit after the unit limit was increased from mere 25 was too much of a hassle. And come to think of it — not very strategic. With the releases of Ground Control (which is not an RTS, but when it did stop anyone) and Dawn of War the era of squad-based (and usually with corridor maps) RTS games have began, as the last dying breath of the genre. Казаки already had slow and cumbersome mechanic of line infantry and Казаки II: Наполеоновские войны were more focused on battles of different troops, than on building.
For some reason in my pre-teen years i decided that Age of Empires is my favourite game ever and was really happy on Age of Empires II release. I even made myself a nickname out of the title (and still often use it). But they weren't really good games then, they aren't really good games now. In my childhood i was comparing them to DOS and 8-bit Famicom-compatible toys, not to the other games of the era. For some time i thought that FPS genre is for dummies, that Hexen is extremely hard compared to Duke Nukem 3D, and i haven't played Doom yet. I've never finished a single campaign, i wasted my time playing the first one in skirmishes with amazing cheats, and the second one in skirmishes with piss-poor AI, and like one or two PvP battles, which just dwindled down. I tried to do campaigns many times, even in HD edition, and unit AI is still one of the worst in the genre, even worse than Dawn of War III (IIRC, first one had same problem).
But unlike first two, this one is actually entirely good. Units actually do what you say them to do, and while card-based meta progression gives you ready packs of units, you still can play it old style, with printing them one by one.
The campaigns are really cool, with full-fledged historical fiction stories and they are mechanically diverse and hero-driven, something akin to Warcraft III: Reign of Chaos. Home-towns and deck-building with progression are plain great, but they are balanced for long play, so you can't top even one nation without extensive grind. And if you want to play as home-town not from the campaign, say, because of your „«'"identity"'»“ or aesthetical preferences or, say, because expansions were released later, you have to do that from scratch.
Vanilla and first expansion campaigns follow one family's fight against secret order conspiracy through generations over some ancient artefacts. Which seems too similar to Assassin's Creed released later.
The second expansion adds three smaller campaigns set in Asia, unrelated to Blacks.
On top of that this game is extremely pretty. The destruction of buildings is already cool, but have you seen the turtles? The local wildlife is detailed beyond any reason and have cute idle animation cycles.