This is simply a set of ideas on how to run a campaign based on East Asian concepts, primarily Japanese.
Classes
Fighter - this can be used for samurai (for higher status characters) or bushi or ashigaru for lower status characters.
Mage - the best match is an onmyouji, which in folklore would summon and control spirits
Cleric/Paladin - the sohei (warrior monk) would be a fair match for either class; the historical sohei was somewhat similar to a European Crusading order
Thief - the yakuza would be the best fit here, with involvement in stolen goods (tekiya) and gambling (bakuto)
Assassin - ninja
Witch - kitsune-tsukai, a person who had the services of a fox spirit as a trickster and illusionist
Weapons are fairly straightforward name changes:
Ono - a battle axe or great axe
Kama - a sickle (treat as hand axe)
Kanabo/Tetsubo - a two-handed, studded war club (treat as morning star)
Tanbo - a short staff, the length from wrist to elbow (treat as club)
Bo - a long staff (treat as staff)
Chigiriki - an iron staff connected to a chain and weight (treat as flail)
Bisento/Naginata - pole arm
Wakizashi - short sword
Katana - sword
Nagamaki - two-handed sword
Yari - spear
Tanto - dagger
Yumi - longbow (uses Ya arrows)
Armor
O-yoroi - heavy lamellar armor (AC 6)
Tanko - banded plate (AC 5)
Karuta - chain and plate armor (AC 4)
Gyorin Kozane - "fish scale" armor (AC 3)
So... Oriental Adventures for ACKS? Sounds good so far.
Color me interested. :)
Because I was doing this when rather tired (and possibly less than 100% sober), I failed to mention that I'd like this to be more of an open thread - everyone toss out ideas. If you've got background in Cambodian history, great! (I know pretty much nothing about Cambodia). Got ideas on adapting Qelong or other adventures? Wonderful! Know folklore and want help translating it into game stats? Good. See how a class would fit into a particular myth? Let us know. I'm certainly no expert, just a halfway decent researcher who's interested in getting things as close to correct as possible without ruining playability.
Bard - Geisha/ Taikomochi.
I definitely want to see how someone would change the rules for a more conformist culture that may not fall along the simple lines of Law vs Chaos. In a world where absolute obedience to a ruler is prized and expected, Order would always have a very strong grip. Would Honor vs Ruthlessness be a suitable axis of development?
Another possible question is economics. Clan samurai weren't typically supposed to make money or adventure: the lord provides for every need they have using stipends, and in return they obey every command. And then start making their own money once granted a fief or sub-fief. It might make for a very structured campaign- but that might be for the best, in the case of players who really don't focus on the stronghold mechanics of ACKS.
Hmm, yeah.. Samurai weren't even landowners in the way we think of European knights and other feudal vassals in the Western world. As far as domain rules go that could theoretically just be handwaved as direct vassals acting as governors and administrators and still following the same ACKS rules, though.
Though unless you're specifically going for a Sengoku Jidai feel for your game, I think Law vs Chaos still works out. Even in the warring states, you'd still have the various peasant and monk rebellions, the Ainu, etc..
I would say that the magic system that you're about to see in Heroic Fantasy Campaign, along with several of the new mechanics such as Heroic Codes, will be of great appeal for such settings.
I ran a very successful ACKS Oriental Adventures game without too much issue. We managed to put a Gargantua on the D@W Battlefield ... Godzilla was charged by cavalry squadrons. It was awesome.
The biggest problem for my band of ronin was that touching corpses was considered unclean, so it was a big hassle to handle looting bodies and carrying dead friends...
The Ikko-ikki rebellions were a blend of social and religious unrest. Most of them were Jodo Shinshu Buddhist, which was a politically active sect that had been essentially outlawed by the Enryaku-ji for not paying tithes to the temple at Mount Hiei. The uprisings generally included unhappy clans (the Kaga Rebellion included the Motoori and Yamagawa, and during the time of Oda Nobunaga they had the Mori, Azai, and Asakura clans as patrons). Many of the ikki were formed by ji-samurai, the rural part-time samurai who mostly lived as farmers; they were essentially the local militias of the time. You end up with a number of factors, religious, economic, and social, that led to the uprisings in various provinces.
I think the Honor Codes will be a big plus to any game, OA or not (Greeks and Romans had their own codes). I also think one thing that would be good (and that I haven't done research for) would be non-human races/classes that fit with the setting.