This thread is a place to discuss any ideas you have for a potential expansion. It would be preferred if your ideas don't involve scraping a major gameplay feature (like "No more Hexes" or "Get rid of global happiness"). If you do have a suggestion like that, at least give an in-depth explanation of what you'd replace that feature with and how you'd implement it with current game mechanics.
Now for some of my ideas:
1. Leaders and leader traits
With DLC adding civs between expansions, simply adding the DLC civs alone into an expansion would seem lazy. My idea is to go ahead and include current DLC in a new expansion, but on top of that, add leader traits to all leaders and give many or all the civs a 2nd leader to chose. The leader traits would be like Civ 4 in that there would only be a handful of traits and many leaders would share similar traits, rather then being like UAs that are completely unique. The leader traits would work as modifiers to typical things that impact every civs. Things like greater food output, reduced maintenance costs, etc.
2. Modified 1UPT/Armies.
My general idea is to allow a small number of units to form together into an army, but still enforce 1UPT rules. In otherwords, a formed army would become 1 unit. As individual units they couldn't share a tile, but as an army they can. The issue with armies is that they have a tendency to become overpowered relative to individual units. I'm not exactly sure how to resolve that right now, but I'd love to hear ideas.
3. Civics
These wouldn't be a replacement for social policies, but rather changeable modified that are unlocked. It wouldn't be nearly as in-depth as Civ 4 civics were, but just ways to refocus your empire a little "on demand" as the game dictates. It might even be as simple as having a "focus". Tell your empire it's war-time and all troops are produced 10% faster. Tell them it's research time and you gain a 5% science modifier. Tell them it's economy time and your gold per turn goes up 10%. Things like that. It may not even be called civics. The point is, I feel like this civ is lacking a little bit of the flexibility of the previous ones. While the other ones had maybe too much, it'd be nice to have a little more then this one.
4. Improved diplomatic victory/UN
Basically, bring back the ability to enact certain global policies as UN leader and build up to diplomatic victory instead of just having it be build UN then win. Also, while we're on the note of winning diplomatic victories, how about instead of the single vote per CS system, we make it so that each nation and CS has multiple seats (preferably an equal amount for all so that it's not "get as big as you can and win automatically" like Civ 4 and Civ 3 were on the UN council. Bring back the limited voter option, so instead of every nation voting for itself, only a few are eligible. Then, have the CSs spread their votes based on how much influence each nation has with them, instead of as an all or nothing based on who has the most. This will make diplomacy victory a bit more of a challenge. Being allied with every city-state might not be enough if all the AIs hate you and vote for the other guy.
Anyways, that's just a few ideas. What are some of yours?
Moderator Action: Merged into the stickied thread (it's partly what this thread is for ).