They had several scenarios that operated e.g. on several moons of an exoplanet, different layers of a fantasy world or different times on Earth, and you could switch between them at least after a certain point during the game. And yes, the maps influenced each other. It was fully working, but because it wasn't as much progress with respect to graphics (compared to regular Civ2), it was derided and became an abandoned branch of the Civ tree.As in how exactly?
When I mention multi-maps, I mean that you can switch between them during the same game, or at least your first map game directly affects your second map game somehow.
So, how was that done in ToT?
The "several moons of an expolanet" also contained humans as well as aliens, with certain technologies only accessible to one side, some of them could be traded to the other, and a key technology depended on both a tradable human technology and a tradable alien technology, so if you destroyed the other side too early, a large part of the tech tree became inaccessible. Certain other techs you gained not by research but by events. Perhaps not everyone's cup of tea, but I've rarely seen a scripted scenario of that quality (Lalande 21185 if you are interested).