Mongoloid Cow: Guaranteeing Competition in the Late Game
I respect your opinion on history, even if it's not the same as mine. I do think we can find common ground on finding a way to ensure more competition in the late game. You believe that could happen if there are more nations in the late game, and that they'd need to be within striking distance of conquest victory.
How do you feel about civil wars? Country's seperating or small outlier secceding, and so forth. Assume, first off, that you could find a logical and systematic way to determine if and how a civil war could occur. Also assume that stable nations would be able to leverage their stability as an advantage, and exploit another nation's instability. Even before the modern age, poorly assembled empires could crumble or even just "crack". And yet they could still have a chance of mounting a comeback if the same thing happens to a rival.
This would ensure that the modern age could be the "age of the comeback". After hitting a stumbling block in the middle ages or industrial age, you come into the modern age with some momentum. Several minor nations exist in the ashes of an empire, and you now race to conquer them before a rival does. It's the expansionism of the ancient era all over again, except this time with more powerful warfare. Sounds kind of exciting to me.
To shift gears completely, I leave you with one other example to consider. In a racing game, because a race can often take a very long time and someone can get a huge lead, game designers have a hard time keeping the race exciting all the way through. A 30 minute race could be decided in the first 30 seconds!
Some game designers have resolved this by giving the AI a "catch up" algorithm, that keeps them within striking distance of the player. The AI cheats not to win, but to keep the game interesting. Most racing games do this, or refuse to intervene no matter how boring the race is. An interesting exception is Nintendo's Mario Kart, where players have a few tools to mount a huge comeback, if they play their cards right.
Food for thought.
Aussie Lurker: Resources
There is no doubt that the modern age could turn on a dime if someone was suddenly denied access to a key resource such as oil.
This could happen in Civ 3, but it's highly unlikely. A huge empire is more likely to have oil in by virtue of their huge geography. And if they don't have oil, it won't take much for them to get a single square. If they have a single square of oil, they can build and power the world's largest army within a few turns. This, in a lot of ways, only reinforces the boredom of the modern age, with the big dog having all the advantages for the last quarter of the game.
What needs to be fixed?
Discovery is a great idea. This would "stall' the quick and easy warfare of the modern age with a new battle over who can prospect those vital resources.
But you should no longer be able to power the world's largest army from a single square of oil. If you're the world's largest empire with a single square of oil, you should have to ration it or find more. In this respect, a small nation may actually have an advantage -- they're spending less oil on day to day life for their citizens. Thus, if a large empire and a small nation have the same amount of oil, the small nation may actually have more oil left over at the end of the day to build their quality army.
And if you were still unhappy with the balancing impact of resources, the game could automatically bias oil towards underdog nations. Meaning oil is more likely to be discovered in a loser's borders than the world leader. I can't help but wonder, if there's a God, maybe he has this sense of irony and balance, with the world's hugest oil supplies in the hands of some of the world's most backwards tyrranies.
Gingerbread Man: Global War
As a side note, Gingerbread Man, I hope you skimmed the last two ideas, because they definitely address some of your ideas. I'm sure you have some additions or interpretations to offer.
But the thing that took me by surprise is your attitude that a global war should be, in some sense, "guaranteed" at one point in the game. If you could do this in a logical and systematic way, this would surely make the game more great than it already is. But if you forced a global war artificially, it might harm the game in other ways.
I would argue that a global war would be lots of fun. But forcing all or most players into that war would be bad. Thus, you need to encourage global war to happen naturally, but motivating neutral players to get involved in other players' conflicts. You'd need to attack the very idea of complete independence and force relationships.
Similar nations (we're both fascist, or we both speak the same language and dress similarly, or both pray to the same God) should be pushed gently into getting along with one another. The way to do this is through the people. Your people become more unhappy because you're not aiding your fellow communist, your fellow christian, your fellow pasta-lover against fascism, Islam, and rice-lovers. Joining in the conflict raises your peoples' spirits, because they feel like you're defending your very way of life. If you click on an unhappy face, they say "we want to know what you're doing about the threat of the Turks!" -- even though the Turks aren't at War with you. Yet.
By encouraging "similar" nations to side with one another, you can let global war form naturally by the player's choices.
Another way to encourage global war is with an idea that popped up called "moral victory". If a nation is committing genocide within its borders and mistreating its people, you should gain a kind of victory point for intervening. If a nation is going on a conquest of its peaceful neighbors, you should gain a kind of victory point for liberating the neighbors and giving the land back to those people.
This would encourage people to do more than just independently wage war in their own self interest, but start getting wrapped up in other peoples' affairs. A global war can only happen when someone is motivated to poke their nose in someone else's business.
Everyone Else: Drawing on History
Here's just a few ideas that have drawn on history, albeit not from times sooner than the modern age. You take a real life example, abstract it and simplify it, and let it be the foundation of a new gameplay element for Civ. I once again pose my "challenge" to other people:
1. Do you think the past 50 years, after world war 2, have been interesting for history in real life?
2a. If so, what are your favorite historical events from the past 50 years?
2b. If not, would Civ's latter ages be more interesting if they had as much expansion and competition as the earlier ages?
Feel free to go into the industrial era, too, for ideas.