Question: What is a good range to work with for deciding the Research Cost and AI Value of technologies? I'm thinking three ranges, one each for early, mid and late game techs.
Sadly, there is no clear-cut answer to this. You have to figure the values out on your own. For tech cost, I usually take a look at similar techs and adjust the value accordingly.
Finding the right AIValue is a little bit more tricky. If the tech is very useful, you want the AI to research it ASAP, but not at the expense of everything else. Using the current AIValues as a baseline, however, is an exercise in frustration. One point more or less can sometimes make the difference between the AI ignoring the tech and the AI researching the tech at all cost. The AI personality and in-game circumstances also play a big role in this. What works for one AI in one game might not work for a different AI in another game (or even the same AI in another game).
It is probably best, if you set all AIValues to a baseline (like 10). Seeing the AI play all by itself will more easily reveal certain likes, dislikes and priorities in the different personalities. All you need to do then is to adjust the values accordingly and sometimes change the category of a tech. It might take a while longer, but, in the end, will be less frustrating (except for the Thalan, they are a nightmare to adjust).
First Civilization: Lady Deidre Skye leading Gaia's Stepdaughters.
I really need to play SMAX again. It's been over two years since my last game.
Currently I have 10 new planetary improvements, among them Gaia Seeds, a new trade good and the Garden of Gaia, a new galactic achievement. Off to a good start so far I think
Adding new improvements is the easy part. Making sure that the AI uses them properly is the hard one. As a guideline, try to refrain from improvements that are only useful on a specific planet. You can make some, but try to make them useful, even if they are placed on a non-optimal planet. Otherwise, this could put the AI in a bad position, as it will not always make the best choice in placing them.