How about a Reputation system.
Local Reputation: Radius of city influence around population densities that have a working government by that Race. Any killing of others would reduce the reputation of that city of that Race which it controls.
Global Reputation: Divided by the number of Races ingame. If a Local killing had occured for a particular City controled by a specific race then that Local City would look upon the killer as such, but the surrounding cities would also have the same view though small. The farther the city, the less of a negative view upon the killer.
*Lower the level of the victim, the worst of a reputation hit is taken both locally and globally.
*Player/Government official victims have a devastating effect on reputation both locally and on a global scale without distance reputation reductions.
*Profession specific classes, crafters, resource gathers, merchants affect reputation severly as it affects the economic cycle of that Local Reputation zone.
No Zone: Beyond any radius of control around cities, outpost, forts, etc. have a Global Reputation hit and not locally, though very small to no reputation hit due to lack of witnesses.
-edit-
Along with a Rep system other factors need to be in place to ensure a proper world to control mass murder. Unfortunatly it coincides with the radius system mentioned above so here goes..
Society : Player Cities
Specific structures that are contructed to provide certain radius of control types...
Barracks - Law enforcement radius. Small, medium, and large. each providing an allowance pool of guards which the player run city may hire up to the max of the Barrack including additional barracks within Population control radius. The barracks will adopt the Population control radius for it\'s own, and ensure it patrols within.
Hall - Population control radius. Depending upon it\'s size, reflects the size of the radius of control. Within the Population control radius other structures may be built within as they all depend on this radius of control. Also houses the wealth of the city, in which case a small pool of NPC\'s are allowed to be hired to ensure the structure is guarded within.
Tax Office - Allows the player run City to collect taxes within it\'s population control radius. Once collected it stock piles until a player who is allowed to access may use the UI to transfer, if not it will default to transfer to the Hall once a day. Very limited number of NPC guards can be hired to guard within.
Outpost - Allows a certain number of patrol units, which patrol within it\'s medium size radius. This structure is to be built outside of the Population control radius. But the radius must be able to touch another radius of control/patrol path.
RoadHouse - This structure provides patrols along road routes. This structure can be built outside of the Population control radius, as long as it can link with that city along a road. The patrols are horse riden guards which go from roadhouse to the edge of the population control radius. Also the RoadHouse can be daisy chained by the number of the City size, max of 4 or Village, Town, City, Capitol. Each RoadHouse sends patrols between them to ensure the chosen road is made safe.
Fort/Castle - Military control radius. This allows military NPC units which not only act as guards with limited partolling of the City but mainly upon the walls and towers. This should deter the WarLords players / united pker\'s. This structure can be built in a city zone, in which case it will adopt the Population control radius rather than it\'s own. It can also be built outside the Population control radius independantly. Ruling within it\'s radius of control with a military standard. This allows Warlords to establish mini kingdoms or legit governments to...take teriitory from another player city. The structure does have it size limits and this does relect upon the number which it can house. Ranging from wood fort to stone citadels. Independant structures to rule with military might have 1/4 the size of control radius than a Population control radius in respect to the size of the structure in question. Also independant structures have access to siege units/equipment.
Toll Booth - For bridges, ferries or city gates. The player has the option to set the rate as well as who it will charge, citizens or non citizens, merchants, or what have you. The size of the radius is limited and should be used in a area which one must pass through in order to collect. This structure does require to be within a Population control radius or within a Roadhouse patrol path. No guards to be hired, depends upon the patrols. The transfer of cash maybe collected by a player accessing the UI to transfer to the Hall or it will default to a specific time.
Marshal\'s Office - This structure provides bounties as well as collecting from completing contracts. This structure will flag any criminal\'s which have bad reputation on a local reputation zone, as well as global should it be that bad. Must be built within the population control radius. Pker\'s would have a hard time getting in, but a thief upon success can have their exploits removed or even reduced by tampering with information within. Then again it\'s up to their skill.s.
Plaza - Allows the merchant player/s to sell their goods on ... event days or what have you. Thief heaven.
Walls, Towers and Gate - No radius projected from these structures though they need to be built within a Population control radius or military control radius. Different sizes and material are optional upon the selection to be built.
Note - Population and military control radius go hand in hand. Choice is how one wishes to control.
Note - Each structure provides a UI to the player in which is assigned to do so to ensure proper maintaince and management are consistant. Interaction with the NPC must be done in order to gain the UI.
Note - Structures can be destroyed, upgraded, repaired and captured.
Note - Currency stockpiled can be accessed by thieves if they are even good enough. Not every structure is safe, hiring NPC guards will reduce their exploits.
Note - Day and Night effect, Number of Guards are divided into 3 shifts. Day, evening and night, as to their numbers on each shift may be manipulated by the player who has access to that structures UI.
Note - Hot zone or OverHead map UI which allows the influence to patrols within city limits. Placing hot spots, depending upon the activities of the players within a city one can alter player questionable activities. He/she who is in control can increase patrols in one area by lowering another. This will allow business districts to form to ensure safty and co-op with local governments as each will depend on one another.
Note - Independant Fort/Castle have no Local or Global reputation zones within. But is considered a No-Zone reputation effect.
Note - City Expansion, additional cities under the same banner with it\'s own government become a vassal state. The Noble who is assigned to maintain the vassel state (player) contributes it\'s share of taxes to the Main Lord of the realm. Main territory and vassel states can share the radius of controls, and intertwine the network of structures to ensure PK\'ers are kept to a state of rarity and thus they must fend for themselves from the dangers of the wilderness. While the organized communitee may continue to adventure in safty.
By creating an enviroment which everyone depends on each other to ensure safty and protecting their way of life/play style within that city. Does infact reinforce their co-op with both government and it\'s population, forming a society as it should. Noobs will come to appreciate the city in which they depend upon for protection, merchandise and support. In turn becoming a member of that city which the local government needs. In times of mass attack from warlords or other governments, aye it will suck, but your protecting something more than just a structure or wealth... but place ya can call home.
-edit- Of course the size of the map would need to be insane, of say like the size of WW2 Online being the largest of all. Also it incorperates a comprimise to both parties as I\'m sure the PK communitee that establishes similar cities, only to house and protect them from the other cities which hunt them down. Rest assured they will be outnumbered greatly only to face mass attack by... non pker\'s =o. Though with a map large enough as in WW2OL, the shear chance of a pker finding a non pker in the wilderness... gah I should win the lotto...
Course in the beginning pkers will be high in numbers though isolated, but in time vanish completly and yet still allow guilds to rp evil if they choose, though a difficult life it will be. In time the filtering system will do it\'s work once the players organize and unite as a society in a realm of RPGer\'s. But that creates a history, year down the line as ppl will write and talk of the dark times long ago and how they have achieved peace among the kingdoms. Yet far off in some distant area of the map, a new order brews...