I don't know if anyone has done this already, but I think the Chinese Spring and Autumn Period and Warring States Period would be a really great setting for a mod or even a new game.
With all the philosophies and great minds that came out of the period, the length of it, the strategic breadth, and the epic size of the armies being fielded at the time, I would totally buy a game or mod set in the era.
The factions might start as
Yan
Qin
Jin
Chu
Qi
Lu
Wu
barbarian factions:
Yue
Rong
Di
Man
Imperial capital:
Zhou
Several rebel factions representing the states of Ba, Shu, Zheng, Cao, Cai, Chen, Song, and Xu.
I'm thinking a game with two sections. One in the S&A era, with a lot of chariots and relatively small battles, and then a section, perhaps triggered by the destruction of the central rebel factions, or by Qi destroying Lu (or vise versa), based on the WS era. Jin would break up into Wei, Han, and Zhao, and battles would be based more on infantry as per the period. The victor would be whoever conquers all of the chinese factions plus the city of Luoyang.
There might be a tech tree, and the rise of the philosophies of Mohism, Confucianism, Daoism, and Legalism.
What do you guys think?