Been feeling pretty crappy the last few days, plus did some other work, so I haven't got any more programming or prototyping done, but since this is a concept development thread, how about discussing some concepts!
Over the past week or two I have been thinking obout solidifying gameplay type ideas, and this is what I have so far:
Campaign
This is pretty straight forward, there would be several scenarios, each broken up into several stages. I am not sure yet whether the stages will take place on different maps, or whether I will just have the player move along the same map, since there will be, theoretically, a very large possible size for maps. I am thinking I will probably use both, and just use a different one for different situations. I want to have a decent number of campaigns, some of which will probably serve as non-intrusive tutorials.
Custom Game
This will be where you basically just create a game and play! This will, of course, be available in both single player and multiplayer. You will be able to do things like pick settings for the map generator or pick a map you created using the editor. You will also be able to restrict things like ages, tech progressions, max population, starting resources, basically completely customize the way the game is played. These games would be set up generally to be played in one sitting, you know, how you would expect most things like this to be. You can expect the AI here to try to finish you off (Or ally with you to tie) as efficiently as possible. That doesn't necessarily mean they will try to rush you (Some AI types might) Just that they generally will not be interested in coexistence.
Civilization
This mode, to me, would be the most interesting. You will be put in a randomly generated world, but it will be much larger. The emphasis will not be on winning a war, but on creating a good civilization. These will be set up to be played in multiple sit downs, because you will have such a large area to work with. Other civilizations will be present (if you choose) and it will be probably more realistic in the sense that they won't be interested in just trying to get rid of everyone else. This will mean that being peaceful with other civilizations will be more common, and will bring up things like opening trade routes with other civilizations. This doesn't mean that war won't happen, because as the game progresses there will be things happening that will create tension between civilizations, a civilization might start to feel too cramped, or multiple civilizations might be interested in the same source of some natural resource. Depending on the AI type for the civilization, they will generally try to work something out with the other civilizations. The fairness of a solution and how quick a solution was reached will affect those civilizations future actions in similar situations. In this way, alliances in this mode won't be just "Oh, I clicked the button that says I am allied, so they won't attack me, but once I am done with those other guys I will just attack them anyway." I am not sure if this mode will have any sort of end game or if it will just continue until you get bored and decide to start a new one. Oh yeah, and due to the fact that this mode would tend to be longer, there will probably not be multiplayer in this mode.