One thing that pops out at when you survey the wildly-diverse range of approaches to domain-level rules in fantasy rpgs is that they roughly split into two camps: the abstract and the granular.
Equally clear is that the divide isn't just a navel-gazing matter for rules nerds—maybe it is, but allow me this dignity-preserving conceit—but one that creates two radically-different play experiences. Just to turn up the debate level a notch, I will say straight up that the more granular camp kicks the tar out of the more abstract when it comes to producing a satisfying game.
Let's lock two stand-out examples from each pole in a cage and see who staggers out. In one corner wearing the colors of the abstract we have Birthright, the younger, sleeker almost-champion of second edition AD&D. In the other corner we have the First Fantasy Campaign, the old, occasionally mumbly heavyweight straight out of Blackmoor.
As we jibber-jabbered about last December, Birthright had many strengths. Running a realm—the vital foot and fist work of such a game—as projected by its rules was, however, not one of them. By most accounts domain management was strangely flat and board game-like.
(Bad boxing allusions end here, dear reader.)
Straight out of the gate on it's chapter on domain rule the tilt toward heavy abstraction is front and center. Take this (my emphasis added):
“Most provinces measure about 1,000-1,500 square miles—about 30-40 miles square, although the exact dimensions of a province aren't important. The vital characteristic of a province is its level, this is an overall measure of its prosperity and importance.”
It goes on to lay out the fact that there are seven levels and throw out some terse details including highly-variable ranges for populations for each.
Next up is a page and a half describing how all political, legal, cultural, religious, and economic institutions thorough out your realm are abstracted into four types of “holdings” each conveniently corresponding to the four main class archetypes: Law (government, fighters), Guilds (economy, thieves), Sources (magic mojo, mages), and Temple (religion, clerics). Again each are mostly just assigned an arbitrary level and poof we are done with the fabric of society.
There are some tidbit details found in them such as the notion that a guild (2) in a province (4) controls 50% of the province's economy. (In passing I have a hard time swallowing the notion that One-Armed Yuri the Master Thief controls half of all the farms, mines, craft work, etc. of an entire province, but whatever.)
The rest of your domain inventory is a grab-bag category called “assets”: armies, courts, fortifications, ley lines, lieutenants, roads, trade routes, the treasury, and loyalty. Armies and lieutenants are the only ones that have some kind of unique to themselves distinctions, the others again have arbitrary levels.
How these elements are put into motion is again highly abstracted. Game play at this level is over rigid, three-month “domain turns”. A ruler of a holding has a certain number of “regency points”, action points for the turn whose correspondence to anything other than that creepy eugenics bloodline connection to the land you rule business is never explained.
The reagent then spends these points selecting actions from a 25-point menu; many of which just add or modify the various levels of the above-mentioned elements. The entire sum of economic activity in your realms for that season is determined with one dice rolled indexed to the level of the province.
As a computer or board game sounds fine, fun even. As a tabletop game, not so much. From the perspectives of both the players and the GM it has so little “face” and conjures up little to inspire the kind of riffing that give tabletop role playing the edge over just about any other game.
Don't you want to know what that “face” really looks like? How do my people make a living? (And how many live exactly here in what amount of territory, for that matter?) Are they harvesting great timbers for ship-building, spinning yak hair, mining glowing ore, toiling away on vast plantations, scraping magical resins, or what? What exact temples and guilds exist here and how do their many respective hierarchies interact with each other? Etc. etc.
These are the details that don't just add color or depth to a setting they add hundreds of little hooks for play.
The BR approach instead is a little akin to me telling you that we are going to take all the little bits that make up your character hand wave them away and just use only your level. We will then take your character through a one-day “dungeon turn” where you can spend a few “adventure points” to buy a handful of actions. After you do this, I cross-reference your level (with a modifier or two) to a chart and then throw a die to determine the outcome of your dungeon turn. Woo hoo!
Next up. let's see how FFC fares after swatting away BR's jabs this round.
Theatrical aside: the counter-posing here is perhaps for effect a bit hyperbolic. All rules abstract some arenas of play in order to favor others. For sure there are fun and crunchy elements to BR and abstract ones in FFC. Many old school systems like the ones found in the 1st ed. DMG and the BECMI Companion set sit somewhere in the middle.
To further muddy the waters there are some rather stark differences in the granular camp between rules that use detail to add player options and verisimilitude (FFC again) and those that use detail, detail, and more detail to create semi-simulations (Chivalry & Sorcery and Harn).
But alas I was trying to tease out a point here and the latter distinction is a cage match for another day.