A strain on whose resources?
Thunderfall's. If you can do it, why shouldn't everyone else who wants to run the same sort of game, or is able to think up a new and novel use for the same concept of subforums be able to? And then we have a dozen or more locked up little sub-forums that eventually have to be "declassified" after they've served their use or shuffled off somewhere else or some other such nonsense.
It makes us put a rather large and unnecessary burden on the Moderation staff, because then everyone's going to want little passworded subforums for their own exclusive uses (alliances, whatever) and then they have to get them lest the Moderators be said to be giving you preferential treatment.
This in turn raises stress between them and us if we all get to do it because of constantly creating or dissolving such sub-forums, or between us alone as some of us get to have them and others don't. In either event it fractures and Balkanizes the forums by setting a precedent. Very bad road to travel down. If you're genuinely worried about cheating I imagine it'd be much easier to just ask for view logs of the particular threads like they do for SGOTM to ensure people aren't looking where they shouldn't be.
If the straight line tech tree is so bad, please offer an alternative. BTW, I see there being about 10 steps (advances) in the coverage and some auto diffusion to neighboring states over time.
It's an alternate world. Why would technology follow the same exact course of evolution it did on Earth? Or even necessarily the same order? By looking at different cultures it's rather easy to see by even an extremely simple comparison, such as China compared to Europe, that a single tree couldn't describe both of them at the same time to any degree of accuracy.
Tech trees only really work on fairly small time-scales with known developments, not vast sweeps of history, as technology is driven by the needs, capabilities, and prejudices of the societies working with it and their interactions with their neighbors. A tree cannot describe that in the long-term unless it's extremely vague (eg: Civ4 tech tree).
If you're doing a wide-angle sweep of history, particularly in an alternate world, the only way to really go is freeform major advances (eg: iron-working) and extrapolate more specific advances (say, Blitzkrieg) based on the sum of those major advances.
As a not terribly good example: The Zinsz people have Iron-Working, and have had Horse Domestication for quite awhile and as a result of this and being nomadic in nature, have developed the stirrup, enabling much better control of their horses. This, combined with their aggressive, raiding behavior against their neighbors and their survival by hunting upon the steppe means they have developed advanced Light Cavalry Doctrine.
You have technologies A, D, and N, and your cultures has traits, 1, 6, and 9, therefore you have products f, q, and x.