Tech/unit relationships question

[Um I would know this how]

I tried posting this before but its not working now, i would like no more than 5 replies please. Anyway here is my question.

I notice that in some scenarios there are multiple units after one tech, but only one of these units is available depending on the civilization. (examples: Midgard, Civil War)
My question is how does one go about recreating this effect when making a scenario?

Unrelated question: What is the easiest way to change the city names for a civ in a scenario only.
I do have Civ2 Gold so this should be an easy question
Thank you in advance

 

[Morten Blaabjerg]

Try this link, and check for the article "Advanced Tech Tree Tutorial" or similar. There is a good description of the phenomena "no,no"-advances and similar concepts, by which you can limit units to particular tribes.
http://sleague.apolyton.net/Guides/tips_main.shtml

Another way to do what you describe is make the preq techs the same for the different units, but the obsolescence techs different for each unit. -So one tribe will have the obsolescense tech of the first unit and the other the one of the second. This way they won't be able to build the unit that the other can.

 

[Um I would know this how]

I see how that would work with two cultures, but how does that work when one has 4 different civilizations each with their own race-specific units? (Midgard again is what i am looking at here)

 

[Morten Blaabjerg]

Easy, you can apply as many units as you like to the same tech, and an equal number of obsolescence techs, so you could do it for all tribes, it's just a matter of how many techs you're willing to use for it.

The most used method, however, is "divergent" or "partially divergent" tech trees, where each tribe has its own tech tree or own branch of a main tree. This can be accomplished by using the "no,no"-techs (which is techs with preq's of "no,no", that other techs are derived from, but can't be researched in the game due to the no,no preqs). This way you can cut off parts of the tech tree from popular research by all tribes.