Hi, it is probably not just my English that I am sometimes 'hard' to understand. :rofl:
In making a challenging game, one might analyze it starting from what you said.
You begin early and conquer some of your immediate neighbors; have a large enough IC/resource base to build an armed forces that is very formidable no matter how 'strong' more distant AI countries get. Add to that, you are simply a better player than the AI.
We could divide the game like WWII, Germany gobbles a few small countries and gears up big time.
The next part is hard to code in AI behavior, have the Soviets wait and muscle up for a few years until you as Germany has become a military super-power. Next is EVEN way harder and considered AI wise still impossible, have a distant super-power gear up as well and hit over large expanse of ocean not in one direction but two and this nicely timed or staggered when you as Germany are deep inside Mother Russia.
So here there are identified at least three phases for the game to develop and handle.
A. Small countries geared to be conquered (in vanilla by the way, France is purposefully hampered with special lines of code, tailered just for this to happen and boy do players bitch if France falls to easy or not at all !! )
B. Second; It is super-power vs. super-power full at it (read Eastern Front) Again a bunch a carefully timed code-lines are utilized to keep the Soviets on track both to gear up on schedule and be 'strong' by 1943 at the latest when war is supposed turn on Germany.
C. Third bring on yet a another super-power, a DISTANT one emphasis important to battle not just the Germans but all across the planet take on and DEFEAT another power which is locked upon endless chains of islands.
Well good luck !!!
Now for us making 'what-if' battle scenarios our task is MUCH simpler yet still very difficult. That is make at least an interesting and challenging two phase game.
A. Again where you fight the first wars on a small scale with immediate neighbors.
B. Again now as super-power find some other AI super-power whether close or far ready to give you a challenge for your life.
So I ask? Has that EVER happened in playing a game? Just point A and B not to mention a on-going challenge thereafter.
From what you said already the answer is no.
So back to point one. Where do set starting IC?
Low, middle, high, or very high?
If too low, nothing of merit happens not even the first A. Unless you carefully start with a loaded deck. That is a hefty OOB at scenario start. For this will afford low IC and even low resources IF you give them a stockpile at start or ally with them.
If middle or higher IC with resources are available at scenario start, it becomes a horse-race to see who gets strongest fastest. And experienced players prove that they will always win this race.
This is the simple breakdown.
Add some of these twists listed below and sometimes you can get the game to do both A and B nicely.
Alliances
Diplomatic prejudices and hampers
Forts and locked troops
Strong starting OOB
Peace modifiers to hamper humans who sit too long building up armed forces
Events that literally cheat by swooping in troops and IC at the 'right' times and 'conditions'
Techs plans and trading schemes that favor an up and coming AI super-power (you hope as a designer)
Keeping the occupying cost high and advantages low
Another nefarious one that CIV II utilized is automatic dog-piling on the human whenever it was numerically 'ahead'. Essentially all diplomatic actions stopped in favor of DoW on the human who had dared to get ahead.
Those are some the rich tools we can use as modders (game designers) to get a 'balanced challenging and perhaps even thus long-lasting game'. Presenting challenges to the player in the formative beginning of the game, middle and ending. A dream....
Yet, I have not yet seen this occur where it is with a formidable AI to boot.
Right now, no matter your settings, they lock in at start-up. In 1.3 it may finally be possible to have different AI strategies in the game after it is going based on WHAT the human does.