A Video Game I want to make...
Where the idea is substantially different is that each civilization is represented by a tableau of cards. This basically means that instead of all the civilizations starting with some kind of special ability, they would all start with the same abilities/set of tableau cards, which they could add to or replace to unlock special unique abilities over the course of the game. As such, there wouldn't be a tech tree either, although maybe tech points or something similar thematically could be spent to acquire a revealed card. Different cards could even have costs in alternative "currencies" if necessary. I.e. some cards could be acquired by spending either science or culture. Another might have a cost in gold or food. I could even have new currencies become available over the course of the game.
Another aspect of the game is the idea of a Nomad. One thing I've always felt lacking in Civilization games (and there isn't a lot) is the fact that you pretty much have to settle where ever your settler spawns first turn. You could maybe move a single space on that turn before settling, but if you wait until turn 2 or beyond you are at a fairly serious disadvantage. One of the cards I want every Civilization to start with is the Nomad card. What it basically does, is give you access to the Nomad unit, which is kind of like a mobile city with certain limitations. Primarily three limitations. First, it can't build most structures (except those that could conceivably be something that can be packed up). Second, it has a limited size of say 3. And third, every time it builds any unit its size is reduced by 1. But if it is size 3 that unit could be another Nomad.
And of course, players could still settle right away or on some future tun. The moment they settle their first city, the nomad "card" is flipped over or replaced by another card that indicates that they can have permanent structures and no longer produce nomads but instead produce settlers. Existing Nomads would still function as Nomads except without the ability to produce further Nomads. Something like that.
Anyway, just a little idea I've been thinking about lately that I wanted to get written down in some way. If I move forward with it, this blog may just turn into the dev blog for the game.