I played as Korea on King. Actually quite easy, and I managed to complete it in about an hour (turn 35 or such). I read somewhere, that one say, that Korea is the hardest Civ in this scenario. Not IMO - because after Japan had lost their initial army, the AI are someway not able to send proper reinforcements (except from the Busan trait). Japan managed to take 4 of my cities, I managed to defense Seoul with 3 hwachas and a crossbowmen. And at about turn 25, their army was thin out, and a push back to Nippon was able in a few turns.
In my next game, I played as Japan on Emperor. The start was quite easy, and I more or less steamrolled Korea in about 20-25 turns. After this, I go for China (with a short war against Manchu), and after I got the first Chinese city (from east), I got problems. The bridge over the river, east from the first city, is "blocked", so every units end the turn after it, and the second city can reach the units here. Therefore it was a pure slaughter here, because I cound't get my units in position, before they there killed by the cho'ko'nus, cannons and the city. So I tried an alternative, and try to "go Mongolia", and attack from the north, combined with an naval army from south. This failed by several reasons:
- My army was too small
- Chinese army to big
- Great Wall are really annoying
- Japanese naval are really weak. Not able to cross ocean with anything, and only got triremes. Therefore you only have 2 to-tile broad passage east of Korea.
- Those bad-ass Turtle Ships destroyed my naval. Seriously, they can almost insta-kill triremes, while you need 3 triremes to take out one Turtle Ship
Maybe I could win by time. But this was only about turn 50, so I surrendered, because I haven't the patience to a long war, which will take a half day or such.
By the way, do someone know if it is only the AI Japan, that got reinforcements at Busan? Or it is difficulty-related?