Rome was undoubtedly great at her height, but so was Han China with a wealth and population to match if not surpass Imperial Rome at her own heyday.
IIRC the time of the Roman Empire was the
only time in history that the Mediterranean world actually outnumbered China in terms of population, with the accompanying greater wealth. As soon as you kids get reunited by the Tang, though, you outnumber the Mediterranean world easily.
Because something did not occur in our reality does NOT mean it could not happen in other reality in the multiverse. In the realm of althist I have seen some truly wild Althists that had things as wild as Korea or the Confederacy ruling the world and enjoyed them for what they were, a departure from our own history, whether they were fantasy or not.
Yes, of course, that almost goes without saying. What seems to be the main complaint here is the disturbingly large number of butterflies involving extremely rapid technological progress in one country, combined with the virtually uncontrolled and unchecked expansion of said country into regions that would be at best difficult to take over. Besides, most of these timelines were developed with the intention to use them as settings for NESes, and it's difficult at best to do that when there is one country that has achieved hegemony. Besides, hegemony is unhistorical (I know that's not a legitimate complaint, but I feel like making it).
All i have heard from you is your opinion. I have not seen any datum that would suggest it is beyond the realm of the possible. Hell it is just as fantastical as any Confederate victory over the Union or Mexico winning the Mexican-American war. Yet I read Confed scenarios all the time. And have seen at least three Mexican victories.
The Confederacy winning the ACW is within the realm of possibility (for an entirely different take on things, see the althist I've posted before, which at the beginning of this thread is
in medias res 
) and requires but one change at a certain point, of which there are several to choose. Even with the Confederacy's survival, though, a lot of people who frequent this thread complain. Too, Mexican victory, given that Winfield Scott was sort of low on numbers and Zachary Taylor was across a desert, isn't out of the realm of possibility, though anything more than a defensive victory is almost completely out of the question. Those require at best one change with minimal butterflies; your TL involves a good deal more of those which, again, are not out of the realm of possibility but seem to most people to be rather improbable. As has been stated but a few pages before by a rather eminent personality in this thread, the best althists involve minimal change and following logic rather than lots of butterflies to get what you want.
Someone asked why would the Romans would want to hold a forest? No profit in it. I based that part on the article I saw here:
The Roman city foundation of Waldgrimes
So as per the most modern archeology the Romans did try to set up at least one city to begin the economic building of a new Roman province. I really have tried to stay within the realm of the possible, and I really do mean it when I say any constructive criticism is welcomed.
Yes, that's very true. I also hold up the examples of Britain, Dacia, and to a lesser extent Gaul (the La Tene culture had better things to steal) as places conquered with very little intrinsic value. And, I suppose, there is the example of Britain to hold up here as a place that the Romans could conquer and hold for a significant portion of time, Romanifying the inhabitants to such an extent that they'll stay Roman for a few centuries, and even
later. However, Germany, being on the wrong side of a cultural dividing line (they were Jastorf as compared with the Celtic La Tene), was also on the wrong side of an economic one as well. The La Tene (like Gauls, Belgii, Celtiberians, and Britannic tribes) had nicer stuff to steal and thus mitigated the costs somewhat of settling the places where they'd taken up residence. And the colonization and Romanification of Gaul was, to a great extent, covered by the excess money from Roman Africa (which had gold coming out of its ears all the way up to the Vandal conquest). So yes, Germany could have theoretically been conquered by the Romans, and held as far as the Elbe. But in my view, Romanification and the construction of administrative and bureaucratic centers from which to run the Chattii and their ilk would have been extremely limited due to the fact that the Roman Empire just doesn't have that kind of money. It'd go on fine for a few centuries, but as soon as we hit the era of the Crisis of the Third Century Rome would be forced to relinquish Germania just like Dacia, although it would provide a handy buffer zone and possibly would lessen the impact of the invasions somewhat, giving us an overall richer Roman Empire as we go into the fourth century. But frankly, the presence of a Roman-built administrative town more proves my point than anything else, because Romans wouldn't need to build anything there if there were any existing infrastructure and thus money. They didn't even have to build new towns in Gaul, and that itself was a pain to subdue.
@Dachs: Yes but he is having the massive expansions
before that third century crisis

. And I seem to disagree with you on how much was solved then (I would use 'a lot', you use 'most'

).
Heh. Maybe I've been reading too much Heather recently; that'd do it.