when your opponent advances to the next age ahead of you, your cost of advancing is LESS.
I finally figured this one out. I had been wondering why sometimes, it costs 200 to advance to classic, while at other times, it only costs 180. (this is both with 2 sciences researched and Without silver, sugar or other civ specific bonuses).
finally I noticed that the cost went from 200 to 180 when someone on the other team advanced first.
so the idea is this- you wait till they advance then you advance. you get a resource bonus....
I do not know that this is consistant throughout the entire game, but I am betting that it is... so anytime they get ahead of you, you get a discount on the amount of resources you need to spend to advance.
I have not tried this, but maybe i will later.
Theoretically you can save a ton of resources if you let someone else (his team or another teammate i think) get to the next level first. the only disadvantage for you will be that they will have the option of advances in research and unit advancements sooner than you... if you play it right, this is for only have a minute... and the only age that it appears that it pays to reach first is the VI industrial age... the reason is that you have first dibs on buying up all the oil as you can at a lesser price and gauging your opponent... otherwise if you are not engaged in battle where an age advancement gives the opponent an edge on unit technology, you win out.
let me know what some of the experts out there think of these ideas... did any of you know that you get a discount like this???
Ill have to watch as I go thru the game and see how much you save in later ages... 200 to 180 is 10 %.. if that is the case, later ages could save you up to 200 in resources and research costs. that 200 is a significant amount imo.