Test of Time is my favorite Civ game. The multiple worlds are really cool, and once you get teleportation (in the Fantasy game), you can teleport units around to worlds they can't normally reach. You get bizarre results when Dwarves terraform Magic Clouds and impassable sea floor terrain, and having ordinary boats sailing through the sky is a hoot.
The extended game is different in that you can play the Alpha Centauri species. Just think -- a whole planet that's yours to colonize and improve, with no fighting. And if you get the Great Library built early enough, you still get its benefits. Late in the game you can go to Earth and conquer to your heart's content.
The Midgard scenario is fiendish. I have not been able to complete it yet, because there are a couple of the quests I can't figure out how to finish.
I love the SF game, because of the challenge of colonizing such different worlds: Lalande, the orbital platforms, Naumachia (the moon), and Nona (the gas giant).
I don't look at the minutiae of computer tech or AI, etc. when deciding if I enjoy a game. If I can imagine a story to go along with it, that's when I consider it a good game.
My username, Valka D'Ur, is the name of the character I use most often in the SF game, and when playing the Stygians in the Fantasy game.
Obviously, my opinion differs from other posters here in that I highly recommend Civ II: Test of Time.
