So how would the camapign look like? Here are ten basic concepts:
1) After Karath Din - the old civilization - fell to an onslaught of Nature, Chaos reigned and men lived as animals in bestial savagery, worshiping the Trickster. But then, 1,600 years ago, the Master Builder fashioned the First Hammer out of stone and wood, and led Humanity in rebellion against the Trickster and the Forces of Chaos. Once free of the barbarian past, the victorious Men built a new Empire out of the ashes of the old, building The City, one of the principal cities of the Empire, on the ruins of Karath Din. Eventually, 700 years ago, the Empire fell due to infighting between its Princes, and city-states arose from its ashes. This is the world of the present - fragmented and, thus, somewhat weak in face of Chaos.
2) The Order of the Hammer (AKA the Hammerites) sternly guards against the forces of Chaos led by the Trickster. Though staunch and sometimes fanatic in their struggle against Chaos, the Order of the Hammer is now quite ossified and concerned with tradition and with stern punishment of criminals and heretics more than with actual struggle against the Trickster. However, the Hammerites hold a significant military might and also benefits from its technological mastery. Lawful Clerics and Paladins are all Hammerites (probably using slightly different classes than in the core rulebook, more similar to Dwarven Craftpriests).
3) Civilization, as a whole, is crumbling under the onslaught of Chaos. Fragmented into wrring city-states, the civilized lands are besiged by wilderness and chaos on all sides. Chaos also seeps through the cracks of civilization and festers in its rotten heart.There are many Chaotic gods, but chief amongst them is the Trickster, also known as the Woodsy Lord. Chaos stands for the savagery of untamed nature, for bestial inhumanity. Where Law is not present in force, Chaos invades, be that vines undermining unattended buildings or the dead rising in vile mockery of the Builder's humanity. Pagans work to bring about the reign of the Woodsy Lord and his Beastesses and Nymphs, and the end of civilizaed life. Chaotic priests will probably use a different class than Cleric (maybe the Shaman from the ACKs Player's Companion?).
4) The Keepers are True Neutral and belive that either extreme, be that of Law or of Chaos, is a threat to humanity. As long as Balance is kept, humanity flourishes. If the scales are tipped, then the Keepers intervene to restore Balance. Keepers probably use the Thief and Assassin classes, but some might use something more along the lines of a Nightblade.
5) There are two main groups of magic-users in and around the City. The first is the Brotherhood of the Hand, a mostly-Neutral mage guild; the Brotherhood follows an Elementalist tradition, and most of its mages take the Elementalist proficiency; while mighty, they usually keep to themselves. The second is Necromancy - quasi-Chaotic meddling in life and death, usually to call forth undead and unnaturaly prolong the Necromancer's life. While illegal, and punishable by death if caught by the Hammers, they thrive inside the cracks of civilization. They usually take the Black Lore of Karath Din (AKA Black Lore of Zahar) as their first proficiency. Ironically, both traditions originate from the lost civilization of Karath Din.
6) The Fey frolick in the wilds. There are two kinds of Fey - the Seelie Court (who are Neutral) and the Unseelie Court (who are Chaotic). Both have a habit of kidnapping human babies from their cribs and replacing them with Fey babies. These Changelings - Fey raised by human parents - are represented by the various Elf classes in ACKS and the Players' Companion. Their social status is quite low in the City, and some of the more fanatical Hammerites hate them (and they get -2 to Reaction and Loyalty rolls from Lawful humans if their Elven origion is known), but they have mighty magicks at their disposal.
7) While some elements of the City might seem modern, on the most basic level this is a profoundly feudal society. Lords - from the lowliest noble to the mightiest Earl (the term I use instead of "Baron" for the City's ruler to avoid confusion with other noble ranks) - have the right to bear arms in public and raise their own men-at-arms and even armies if they so desire. The Order of teh Hammer is also heavily armed. And so are the various criminals in the City, usually posing as men-at-arms of various "nobles" of the type of Ramirez.
8) The City's underworld is ruled by the Wardens - mighty crime-lords, usually holding a formal noble title of one kind or another, who fight each other for their share of loot. Independent thieves might encounter trouble from the Guilds and Wardens who, naturally enough, do not like competition by independents.
9) Some areas of technology are far more advanced than in 'vanilla' ACKS, though most follow the ACKS norms. Steam-powered generators power elevators, pumps and forges, as well as electric lights. These technological comforts, however, are relatively expensive, so even the average noble - or, indeed, the current-day Hammer cathedral - uses torches instead of electric lights on many occasions. Electric alarm systems are also common, though often primitive and relatively easy to tamper with.
10) Beasts of all kinds, eincluding beast-men, roam the wilds and even invade the less-well-guarded parts of civilization. The most common are Giant Spiders, Cray-Men and Burricks. In wilder areas, where Chaos holds sway, civilization is besiged by Spider-Beasts, Bug-Beasts, Snake-Beasts, Rat-Men (who are NOT lycanthropes in this world but rather Beastment who replace Orcs), Goblyns, Bugbears, Ogres, Ape-Men and Tree-Beasts. Undead abound in all Sinkholes of Chaos, even inside civilization, and include Zombies, Greater Zombies (who are more similar to the Zombies in Thief: Dark Project), Haunts (powerful undead swordsmen and archers), Fire-Shadows, Apparitions and Ghouls.
What do you all think of this?