So, the wildy feels a little lonely. I feel this idea, in general, would give more incentive for people to PK and maybe revive this server a bit or make it stand out. The following is just an example. It could be implemented in a completely different way:

-----------------------------------------Mercenary System-------------------------------------------------------

-A player can put out a hit on another player (announcement made on server? hit is indefinite in time until it is fulfilled? maybe anonymous?)
-The player seeking the hit has to go to the "Mercenary Guild" (or whatever you guys want to name it) and enter the targets name.
-This costs gold from the player seeking the hit (Could be any amount or a minimum) that will be held in escrow and will be used to pay the mercenary for killing the target.
-Once a mercenary kills the target, they must pick up their bones (Could change the bones that players drop when they die to read "[Player name]'s Bones") as "proof".
-Mercenary goes to "Mercenary Guild" and fulfills the contract by giving an npc the target's bones to claim their reward.

*There could be a limit of contracts a mercenary could complete per day to help prevent abuse

-------------------------------------------Bounty Hunter System----------------------------------------------------------

Now this is where Bounty Hunters come in as an opposing/balancing force to Mercenaries/Outlaws and pking in general. The more someone attacks and/or kills other unique players the more a price grows on their head and they become "Outlaws". Maybe indicate it above their head with a specific color skull for the severity, or some other indicator. When someone is skulled an announcement is made on the server as normal "[Player name 1] has attacked/killed [Player name 2]." then immediately after another announcement "The kingdoms of Geilinor place a bounty on [Player name 1]'s head. Bring them to justice!" Whoever kills them gets the reward when they turn in their bones to the "Bounty Hunter Guild" (I'm sure you all can come up with a more creative name).

      White skull - This player has attacked or killed 1 player and 5% increased damage, bounty reward 25k gold
      Yellow skull - This player has attacked or killed 2 players and has 10% increased damage, bounty reward 50k gold
      Orange skull - This player has attacked or killed 3 players and has 15% increased damage, bounty reward 75k gold
      Red skull - This player has attacked or killed 4+ players and deals 20% increased damage, bounty reward 100k gold +25k for every
                       additional person

**The skull erases after a period of time or once that player dies like normal (Maybe the time being skulled increases based on skull color?)
***The extra damage an outlaw gets from Zamorak is to help balance out the many players that may be hunting them down and tie in with the theme
****Disallow the bounty if someone kills someone from the same IP to help prevent abuse. and/or a built-in timer for how often you can receive the bounty reward. i.e. once every 24-hours.

----------------------------------------Zamorak's Influence-----------------------------------------------------------

Incentivizing Outlaws to stay in the wilderness:

This would give Bounty Hunters opportunity. Outlaws can get an appropriate reward for staying logged in and in the wildy until the skull expires (maybe they must be in level 20 wildy or higher and remove the ability to teleport in any level of wilderness). When you skull you would receive a message like:"The mark of Zamorak has appeared on you granting some of his power. You are being hunted! Flee deep into the wilderness and away from civilization until your sinister acts have faded! The hunt expires in [X] minutes." with the countdown in small print in the bottom right corner of your screen "XX:XX". If you last the duration of your skull in the wilderness without dying, leaving, or logging out, a message will appear "The passing of time fogs civilization's memory. Your name and infamy long forgotten...You can safely leave the wilderness." You can then go to a new NPC called "Follower of Zamorak" to claim your reward "You've gained Zamorak's favor by sewing fear and death. Now take this reward to further his chaos!"

Deterring Outlaws from leaving wilderness:

Outlaws who are skulled beyond normal White Skull can be attacked by other players outside the wilderness but cannot initiate an attack on un-skulled players themselves. Maybe some kind of RNG event can occur the moment an outlaw steps out of the wildy, and frequently thereafter if they leave the wildy, where a very high-level NPC named "Bounty Hunter" can appear and attack the skulled player as another deterrent from them leaving the wildy and trying to hide in a remote location to wait out their timer. Their banks could also become unavailable for the duration of the timer, with the bankers expressly refusing to serve a wanted fugitive with the Mark of Zamorak. It would prevent Outlaws from banking everything and just sitting at the bank for food as they fight off NPC Bounty Hunters or other players while the timer expires. Maybe all NPCs in general would refuse to talk for the duration.

Alternatively, players who are skulled could be outright prevented from leaving the wilderness at all before the skull expires. Trying to leave might stop the player and read "A bounty is on my head right now. It might not be a good idea to return to civilization...". Logging out could pause the timer so that they would still have to pick up where they left off and renew the bounty announcement. Or not pause the timer, but they would forfeit any Zamorak reward. A lot of ways to implement this.

-----------------------------Conclusion/Final Thoughts---------------------------------

-There can also be certain milestones with rewards, or perks, for Bounty Hunters and Mercenaries at their respective guilds.

-Maybe the guilds can take a small percentage cut of the mercenary contracts to act as a money sink for the server.

So if anyone thinks this idea has potential or not let me know. Point out what I might have overlooked that could be a problem. What would you guys add/remove/change and why?