I haven't actively gotten to do a game like this yet (my players voted for Nordic, curse their hides), but here's some of the ideas that were tossed around:
- Three Kingdoms features the quote "The Empire, long divided, must unite; long united, must divide. Thus it has ever been." That practically demands to be enforced in game.
- My wife planned on playing a bard (and screw Oriental Adventures' "Bards shouldn't be allowed because they break the mood" tripe). The idea was that she was the daughter of a woodcutter and a fox-spirit (quite beautiful, and lightly exotic) who was taken to court on account of her beauty but then trained as a strategist (a la Zhuge Liang and Sima Yi) by someone who noticed her intelligence. Her high Charisma and bardic spells represent the blessings of her fox heritage, while her oratory skills represent the strategist — offering tactical advice and gesturing with her fan to provide morale bonuses and so on.
- Outlaws of the Marsh is another great book with lots of inspiration; 108 notable bandits, with notable abilities and really, really great nicknames. ("The Timely Rain." "Black Whirlwind." "Golden Dog." "Ten Feet of Steel." "Demon King who Roils the World.") I also recommend Lloyd Alexander's "The Remarkable Journey of Prince Jen" — it's a young adult book, but very accessible. Finally, Larry Gonick's Cartoon History of the Universe, Volume 2, has some very abbreviated but easy to follow highlights of interesting things that happened in ancient China: intrigues, murders, wars, etc.
- Something having to do with the Four Directional Beasts is always cool as an overplot, be it hunting down artifacts related to them, four rival kings or perhaps trying to parlay with the great beasts themselves. You could use the traditional four (the Black Tortoise of the North, the White Tiger of the West, the Red Bird of the South and the Blue Dragon of the East), or devise your own.
- Shapeshifting monsters are particularly appropriate: aranea (only called "goblin spiders"), wererats and weretigers are just a few that leap to mind. All ogres should look like ogre magi; horned, tusked, brightly colored skin, sometimes even with animal heads (particularly horse or ox). Mongolian-style centaur "horse lords", orcs riding elephants in the southern jungles, yuan-ti (with psionics defined as "chi powers" if they appear at all).
- Druids, with a few tweaks, might make great "dragon-speakers," drawing their power from the will of the dragons that govern heaven and earth.
- Evil eunuchs. If there are eunuchs, they've got to be evil and power-hungry schemers. It's like a rule.
- Wars between sword schools. Hopping vampires. Ruined temples haunted by ghosts, spirits or other monsters. River pirates. Young lovers fleeing arranged marriages. Court intrigues. Strategy games. Devious weapons of mass destruction being tested on condemned criminals. Wise magistrates that act as the PCs' patron at lower levels, and corrupt magistrates that must be opposed. Clay tomb-soldiers.
That's the sort of stuff I'd use. And, of course, there's always Jet Li's Hero: if your players watch this, they may look askance at the state of Qin.
