Each civ has an immunity percentage. This rating is determined by number of hospitals (and other health buildings and sanitation(sewer systems) buildings) comapred to cities, and the ammount of diseases rampant in your civ (the more, the higher your immunity rating). Diseases are caused by the size of your cities, the closeness of your cities and the number of civs you have contact with. Diseases simply knock off a few population each turn (using x10 system, so they don't really have a great effect). Sounds complicated, but all you see is the percentage, the computer calculates it. You might have a list of causes so you can try to increase your rating.

When you make first contact with another civ the immunity ratings are compared. If one civ's immunity ratings is 25% or more less than the others, a civ wide epidemic occurs, and keeps occuring every turn until the difference in immunity ratings is less than 25%. Since the exposure itself raises the immunity rating, the epidemic would burn out after a few turns. This epidemic would not be your average disease, it would cause massive damage each turn it is in effect, so even though it only lasts for a few turns, it would be catastrophic.

I think players would want to keep their immunity ratings as high as possible. Even a powerful civ could be crippled by an epidemic, just as IRL.

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- Biddles

Could you explain more about the percentage in immunity differences? Does this model assume one germ type per Civ? And "immunity" is a defense against ALL the various germ types?

Also to consider would be latitude and longitude as well as oceans. I.e., civ's living on the same continent, side by side along the same latitude, would naturally be exposed to the same germs even without contacting each other. However, crossing oceans, or meeting civs living on the same continent but at different latitudes (i.e., north or south of them) they would come into contact with new environments, ergo, new germs.

raingoon: Immunity percentage. If you had never encountered a strain of influenza before then you would be highly succeptible to any influenza strain. Whereas if you had been exposed to a large number of influenza strains then you would have a greater chance of surviving a new one. In essence, the greater number of diseases that you were exposed to, the higher chance you have of quickly overcoming a new diseases, because you would have encountered something similar before. I am not sure if this is how things really work, but I think they do. Since the immunity percentage takes into account number of diseases (along with health facilities) so immunity rating is kind of like immune strength, 100% being invincible strength 0% being totally succeptible.

UltraSonix: Germ warfare, exactly the point of this whole system. What's the fun of having it if you can't wipe out a civ with it without declaring hostlilities . In that scenario it would be useful to 'collect' diseases...

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- Biddles

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- Biddles