Originally, Meier designed Civ as a real-time game. Taking inspiration from SimCity, he wanted to have a player's civilization grow around them. In actuality, players became observers. The mantra was "it's good to be king," but this wasn't coming across in real-time. Then, the game switched to a turn-based design and the "lights flicked on".
For a game that has since become "the poster child" of turn-based gameplay, it's rather surprising to learn that it started out on the other end of the spectrum.
Meier also wanted to have each player go through a rise and fall in a playthrough of Civ. Once the player got to a certain point, something would happen that would cause their leader to fall from power. Then, the player would have to rise up from the ashes and achieve even greater things than before the fall. Instead, most players just reloaded a previous save game to try and avoid the fall. The concept was scrapped.
Finally, the original technology tree for Civ was mysterious and randomized. Meier didn't want to present a linear tech tree to the player, because he didn't see it as realistic.
"It seemed wacky that you would be thinking in 3000BC, that you would know if you researched iron working that someday you would have gunpowder and then nuclear weapons," said Sid in his presentation. So the tech tree was randomized.
Players would just try and find gunpowder in the tree. The playtesters did not like a randomized tech tree and so Meier, against his design wishes, set the tree in stone.
There you have it. Civilization could have been a real-time game with random tech trees and a point at which all your progress was lost. If you ask me, these designs were scrapped with good reason, but it's fascinating to learn what it took to get to that point.