Noble difficulty, 51x51 map, normal speed (not epic). I was attracted by Gongsun Zan's special ability, mounted units ignore city defense. I always hate building/transporting stacks of cats or trebs. I started the game without reading more. Ack! Yuan Shao shows up with 6 swordsmen, 6 cats and other stuff! Fail. Restart. Fail. I decided to approach the start position like a wargame puzzle, and found a solution. The key is to delay until you can get a pasture and a third swift rider in your capitol.
I actually gifted the small western city to Liu Bei, hoping he would be friendly enough to declare war on YS and divert his attention. This wouldn't have worked anyway because he's too far south. But this made YS focus on my middle city with 150 defense, and he bombarded it for a number of turns. Just before he attacked, I flank attacked with the three midlevel swift riders. I had built a couple of crossbowmen and stacked all the archers there, so I could then sally out and kill the stack.
The swift riders weren't badly damaged and they leveled, so I took the offensive. Most of YS's nearby cities had 1-2 archers, and a legion swift rider can take a city archer without too much trouble. So I quickly had all but two of YS's cities by about turn 30. This is already a kind of victory, I think, to survive the initial attack.
Phase 2 was to build an economy. As you can imagine my economy was poor since this region is mostly plains. Build workers, switch to Confucianism for the +50% improvement build speed, and keep turning out crossbows and eventually elite archers to protect all these cities. I had the two homeland cities building swift riders and my main hero had the Frontal Assault promotion, which does 25% collateral damage. Even better, now I really don't need crossbow/cat/treb stacks for city cracking. Swift riders are a little expensive but I can take 2-3 units from his legion and throw them at a city like you would normally throw a crossbow/cat stack to soften it up. I marched down the center part of the map and wound up at Cao Cao's western border.
I am in third place on points and I'm about to build my Forbidden Palace at YS' capitol, Ze. I'm going to have a little trouble with river crossings since all the cities in the north are carefully placed one square away from the river, so the opportunity to build galleys is very limited. I am pretty sure this position is winnable, but I have found that by even turn 150, the game gets to be a bit of a grind. Even with autobuild cities and rally points, there is a loop of build stack of doom, crack a city, wait a couple of turns for damaged units to heal and reinforcements to arrive, and repeat. I have eliminated about five players which only leaves about 20 more to go. And this is the smallest map available.