Conquest

This is a fractal, system-agnostic structure for making the control of territory a gameable thing at your table.

Example: a thieves guild struggling for control of the city's criminal underworld. 

Example: a lord's war to suppress the forces of chaos in his domain. 

Example: two armies fighting a civil war. 

Example: a cult enforcing orthodoxy in its parishes.

Why Is It

You want something like this if you want domain-level play. Or if you want your dudes to be hustling to control territory (or whatever idiom you may be employing). And you want this kind of thing to drive play or at least be an optional focus of play.

Me? It's the point of the campaign I'm currently running. It's about a thieves guild trying to take over one particular city, pushing out all the competing criminal interests, and trying to insulate themselves from the law.

To incentivize, you could give XP for each territory held per cycle, or you could just say (as I'm doing), "The object of the game is to control the city."

How It Works

I'm going to give boring but informative bullet points. But, before that, examples:

Example: taking Helmsfordshire will leave the rebels powerless.

Example: the Krayeerb Krew just burned down Sandercot Provisions, and now their drug dealers are everywhere.

Example: well, since we assassinated the vicar, we're running the charity BBQ this year, and that'll give us enough good will to get away with it.

Example: I just accepted my childhood trauma yadda yadda.

In general, players will see: oh, these people control this area, and we control this area, and these other people control that area. Seems like we should make a move here. They make a move. It either goes well or it doesn't. Maybe they drive the other gang out with a bloodbath at a birthday party, or they suffer heavy casualties in situ. They then either control that area or they don't, and maybe they lost an area in the process. 

(OPTIONAL: When the cycle (of whatever length: day/week/hour/extended rest) comes up, you get the resources or suffer the vulnerabilities of the flags you hold. So, if the alchemist you're "protecting" comes up vulnerable this cycle, he's got nothing for you, and the explosion in his lab injures one of your low level gang members, but at least you still exert control the alchemist's neighborhood.)

1. Determine a realm of conflict:
1. universe
2. globe
3. kingdom
4. city
5. street
6. family
7. self
8. whatever
2. Divide that realm into control points generically called flags.
• Call flags something more suited to your realm if you want.
• The more flags, the longer things will take.
• You will begin with a certain number of flags per realm. More may or may not be added, depending on the kind of thing you're doing. 
• Some flags may contribute more or less to dominance (q.v.)
3. Generate the particular flags in prep or in play. 
1. give it a name
2. give it a concept
3. (optionally) give it resources and vulnerabilities (q.v. in a bit)
4. A realm is fractal. You can detail as many sub/super realms as you wish.
5. A realm is considered conquered by a faction when that faction holds a number of flags sufficient to meet that realm's dominance level.
6. Determine the dominance level of the realm in question. You can make the dominance level whatever: plurality, majority, 80%, all, etc.
7. What it means to hold a flag is a necessary subsystem.
8. Any mechanical effects of holding a flag (beyond contributing to dominance) is an optional subsystem.

That's About It

The above is actually the hardest part. It's the skeleton that moves this whole thing. However you do the subsystems, it should still work. Nevertheless, more detail and examples:

Holding Flags

• To hold a flag you must either take it or start with it:
• a gang might start with Lowden Street as a flag they hold
• however, Brockton Street, just one block away, is run by the Krayeerb Krew
• to hold that flag, they've got to take it
• what taking it means will depend to some degree on the actual game you're playing
• in D&D 4E, maybe you have to win an encounter of a certain difficulty to take a flag
• you could play cards for it, I dunno
• if you're doing a Pokemon game or whatever, do a Pokemon fight!
• in other words, use whatever procedures your system provides explicitly or implicitly to make this happen
• me, I'd just say, "You head over to Brockton Street. [clatter clatter] 6 KKs are getting high on the stoop in front of the alchemist's shop. What do you do?" Then they do something that either:
• establishes their taking of the flag
• establishes their non-taking of the flag
• establishes, whatever the above, that the current holders of the flag know what's up and may instigate gang war / retaliation against the party's institution
• etc
• so do the above
• then: repeat

Example: the party sees 6 Krayeerb Krew toughs getting high on the stoop outside the alchemist's (I'll name that shop in the moment, Phil's Philters or something). The party immediately goes medieval on them and stakes their heads up outside the block. The party's gang now has taken the flag and holds it for now.

Reconquest

Presumably you can come up with some procedure for challenging the the dominance of the party. 

• treat days as dungeon turns; roll % for random encounters, where the encounter is: they try to retake their flag, or they do in fact retake their flag; what do you do about it? 
• treat days/weeks/mechanical events (like 4E extended rests) as hard moves or encounters, and challenge their dominance then
• do a kind of Fortunes/Wealth move inspired by Apocalypse World: at the start of some cycle (session, day, week, rest), have some character make a check that determines how bad things have gotten among the flags/realms they hold. 

Resources

• Resources are optional
• Read Apocalypse World; it's like the Hardholder's Wealth move
• Briefly: assign each flag (either individually or by tagging it with a general resource) a resource it provides when things are going okay (like, +10gp, a potion off the common magic item list, whatever), and the party just has access to that without discussion; it's not something you have to worry about in the fiction. However, if things are not going okay ("going okay" determined per "Reconquest" heading above), you do not get its resources, and you instead have to deal (if you want its resources again) with its vulnerabilities, like "shipment intercepted by gang," "dealer arrested," "too neurotic to help right now; in sanitarium". Then the players can either say "whatever" or "let's bust him out!"

This Is Actually All You Need

You can fill out the rest from here. I'm going to do so for my own campaign. I'll post it when it's all gussied up as an example, but it's basically all busy work from here:

• deciding how many levels deep you want to go (how many realms?) 
• deciding dominance level per realm
• generating the flags in prep or creating your tables for doing so in play (or just improvising)
• determining your reward/vulnerability cycle, if any