Good idea! I think I'll do it. Of course, the "loser" would switch to Drake's Voyage probably, as Naval Doctrine is researchable relatively soon for both Spanish and Portuguese (the English start the game researching it, while the Spanish and Portuguese are researching other things but will be done with those soon enough). One flaw of CivII I always hated was that a civ could "switch" to another wonder, without any shield loss no less.... As if you could start building the Cure for Cancer and, when somebody discovers it first, WHAM! Your Hoover Dam's most of the way done from nothing! Maybe I can counter this by slowing the tech paradigm, although I can't do this too much else the tech progression would seem too slow in real time (my proposed last-turn year is 1900).
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Well, I found out that you can't have any barb cities unknown by EVERYBODY--I tried setting up the dummy civ for the barbs to take out, but found you can't restart an eliminated civ after they take the old one out (and I left the "don't restart" box unchecked for this very purpose--hmmm...). SO, either the Chinese start by knowing all of Polynesia, Australia, and Western North America, or there's another way to do this. I SINCERELY hope the latter (China was just TOO isolationist at that time for such geographical knowledge), any suggestions here?
Some questions about barb "civs":
How fast can a barb "civ" discover tech? As quickly as any Despotism civ of comparable size? Or slower?
And I know certain unit slots are used by barbs to "upgrade" units from those previously generated (i.e. at some point in a regular game, you go from barb horsemen, to elephants, to crusaders, to dragoons, etc.), does this mean that a barb city won't ALWAYS produce those units "seeded" by the original unit that conquered them? What other implications do these slots have? Do I need to be careful what I put into those slots? (Actually, I wouldn't mind at all having barb units advance in strength over time--i.e. the later you wait to conquer, the tougher it will be.)
When barbs gain techs, can they USE them the same way a normal civ would? I.e. can they start building better defensive units, or do I need to event-add them (something which could take up all my event space too quickly)?
Can barb cities build improvements? Will they always maintain those improvements I've started the cities with?
I've put palaces in a few barb cities (some cities, like St. Petersburg or Osaka, I want unbribeable). Will these be maintained?
I have the European Russian cities as part of the barbs, yet I want this area to be as formidable a barrier as it really was to Eastward expansion--i.e. I DEFININTELY want this particular area to "keep up" with the ground-military tech of Europe. I even thought of sacrificing the Italians (but who would get the Italian cities?) for the Russians as a civ--but that would destroy the character of the game, I think (boy, I wish you could have more than 7 civs!), being as it is about a contest for maritime supremacy. Must I use events, or is there an effective way to automate the process?
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Other notes:
You may have noticed there is no French civ. I started with the 6 powers represented in "Uncharted Waters" (one of my favorite "other" games)--Spain, Portugal, Italy, Holland, England, and Turkey--and added China (I DEFINITELY want them as a playable civ). When mapping Europe then, I was thinking not so much in terms of DIRECT political control, as in terms of "spheres of influence" (a UW concept). So when it came to drawing up that territory which was historically France, I put Bordeaux with the Portuguese, Marseilles with Italy and Paris with the Dutch. I didn't really know how else to do it, and I believe Paris was more "northern European" than the other French cities represented. Actually, if I can recall from memory (I'm at work now), here is the working breakdown of European cities by civ:
English--London, Plymouth, Liverpool, Newcastle, Glasgow, Dublin, and Belfast (and maybe Cork, with the Book of Kells, although I've so far had it with Portugal to "balance" their relative lack of cities in Europe--also being a possible Catholic strongpoint when that distinction becomes significant, which it will). Debating whether to give them some Scandinavian cities, rather than the Dutch having them all.
Dutch--Amsterdam, Antwerp, Paris, Hamburg, Copenhagen, Bergen, Oslo, Stockholm, Lubeck, Danzig
Portuguese--Lisbon, Bordeaux, Cork (possibly), Madeira
Spanish--Seville (capital), Madrid, Barcelona, Cartagena, La Coruna, Tenerife, Tangier (in Morocco) (note: when DID the Spanish really start penetrating Morocco? I have Fez for the Turks.) (second note: I'm thinking of eliminating La Coruna and replacing it with Bilbao, so I can create Oporto for the Portuguese, but I'd still have to expand Iberia, which is already slightly bigger than scale.)
Italians--Rome, Genoa, Venice, Naples, Catania, Marseilles, Vienna, Munich, Ragussa (Dubrovnik), Athens
Turks--Istanbul, Budapest, Belgrade, Odessa, Sevastopol, Trebizond, Smyrna, Antioch, Beirut, Jerusalem, Mecca, Aden, Muscat, Hormuz, Doha, Baghdad, Shiraz, Isfahan, Tabriz, Meshed, Suez, Cairo, Alexandria, Tunis, Algiers, Fez (note: Turks have a lot of cities, but are significantly behind in key tech areas (particularly in naval techs), so hopefully this balances.)
In Europe, barbs get: Moscow (palace), St. Petersburg (palace), Kiev, Tiflis, Samara, Volgograd, Riga, Helsingfors, Keflavik (Iceland). They also get Tripoli (pirates galore!) in North Africa, and most of the rest of the world.
Any suggestions for improving this breakdown? I'm wondering about making the Dutch smaller (they WERE a bit of an underdog in Europe then, at war with Spain), like I said maybe giving some of their cities to the English.
Oh, and as for colonies elsewhere, only Spain and Portugal start out with any, representing what they historically had at 1500. The Turks have Zanzibar also.
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Unfortunately, I may have to redo the whole shebang again! I failed to notice from previous such doings that you CANNOT (at least as far as I've been able to figure out) add rivers with the "change terrain at cursor" command, and I forgot to put rivers in China before building the scenario on my worldmap! WHY can't you add rivers?!?

Sure, I can put in "ocean" squares to represent navigable channels (which the Yangtze was), but the significance of river squares for trade is lost, and besides the map just doesn't "look right" anymore. (I also forgot the Volga, too.) Actually, if I DO redo the map, I can correct some minor discrepancies that have also bothered me some (like the necessary foreshortening of South America at the bottom, which came about since the Cape of Good Hope, about ten degrees further north than Cape Horn, was near the bottom of the map; and the distortion of Siberia/Alaska near the top). Besides, it will give me a chance to rebuild the tech tree from scratch, because I already have changed too many things with it anyway....
Well, I'll keep what I have now and do another map--if I like it better, I'll use it.