In order to build a successful online game, you must build a sense of community among your players. One of the biggest challenges to successful community building in online role-playing games is tempering the problems caused by players killing or stealing from other players. Such problems are known more generally as player-vs.-player conflict (PvP). Over the course of time, different games developed by different companies have sought to control this problem through a variety of methods. This article touches upon PvP control strategies used by Simutronics Corp., where I am currently employed, as well as strategies used by Origin Systems in Ultima Online and by 989 Studios in its game Everquest. While there is no single correct way to maintain order in an online game, by examining these companies’ strategies for restraining nonconsensual PvP, I have created a set of general guidelines that should be considered when designing an online justice system.

The Current Methods

While existing systems for controlling PvP show some very creative design solutions, each of the following strategies nonetheless suffers from certain flaws that arise from the different priorities assigned to game play elements.

Administrative Control (Simutronics’ Gemstone and Dragonrealms) Simutronics gives its players wide leeway in resolving conflicts among themselves, and generally limits its hard-coded restrictions on attacking other characters. New players may not be attacked and are not strong enough to harm one another. Stealing from a person’s inventory is limited to coins and small gems, and corpse looting is either not possible (as in Gemstone III) or has safeguards that allow careful players to prevent it from happening (as is the case in Dragonrealms). The leeway afforded the players allows the responsible players a great degree of freedom in how they play their characters. To balance out this freedom, though, Simutronics strictly polices its player base. Its players’ terms and conditions agreement, for example, states, “What is not acceptable is to initiate combat against unsuspecting victims. Anyone exhibiting such behavior, especially one who chooses to prey upon weaker players for his or her own enjoyment, may be in violation of…policy.”

“Unsuspecting victims” can be a difficult standard to enforce. It’s fairly obvious when someone is on a mass-murder spree, and we remove such characters from our games immediately. If the offender is an experienced player who knows better, we generally penalize the account with official warnings and restrictions from playing for a period of time. If the player is new to our game, we explain our policies. If any player is unwilling to abide by the rules, Simutronics usually recommends that he or she try a product better suited to his or her tastes.

Simutronics’ methods are effective for controlling those players who understand the rules and deliberately choose to violate them. The system’s main weakness, however, is in handling conflicts in which the two parties disagree over whether consent to violence was given. For example, if player A makes a few choice comments about Player B’s suspected lineage, and Player B attacks, is the conflict consensual? Some Simutronics staffers would say consent was implicit in the insult, but others consider consent to be something that must be explicitly stated by the victim prior to any attack. When staff tread such nebulous ground, they’re fighting a battle that is impossible to win. No matter how they handle the conflict, their intervention often creates hard feelings among the players. Resolving these squabbles also uses staff time that could be spent on game development, requiring a higher developer-to-player ratio than would otherwise be necessary. Simutronics has made the choice to incur these higher costs in order to maintain games in which our customers may play in relative safety from arbitrary attacks. Whether such a solution would be viable in another game depends on the developers’ goals and budget.

Player Policing (Origin Systems’ Ultima Online) Ultima Online’s developers decided to forgo administrative policing and leave its justice system entirely in the hands of the players. Raph Koster, Ultima Online’s lead designer, said Origin designed the game this way in the hopes that, “given the tools to police their own environment, [players] would do so…. Our experience was that every method of administratively imposed policing either failed or led to intense resentment of the administrators of the game. We were particularly concerned because traditional models on MUDs for enforcing social mores were very administrator-intensive, requiring a large number of skilled administrators willing to devote a lot of time to soothing ruffled feathers on the part of players who felt wronged. In a commercial venture of a large scale, we didn’t think this was sustainable.”

Allowing your customers to police themselves is a noble goal, but one that is difficult to implement. The most infamous result of the Ultima Online hands-off policy was the gangs of player killers (PKs) that formed. Such gangs would station themselves at key locations in the game and ambush any poor soul foolish enough to travel with a group smaller than a mob. “I just got PK’d,” was a refrain commonly heard outside the game’s banks, where naked adventurers would come to beg for money to re-equip themselves. Some players formed anti-PK militias, but, as Raph says, they were “inadequate for handling the problem of player killing. The actions of the few police were both insufficient in quantity and inadequate in severity to curb the activity of the player killers and the player thieves.”

In response to the problem, Origin instituted a variety of tools to allow the players even greater control over their environment. Under the current system, all characters begin the game flagged as “innocent,” with their names highlighted in a bright, happy blue. Steal from, attack, or loot the dead body of an innocent — including an NPC — and your character’s name will be highlight gray, branded a criminal and open to attack by anyone. Kill an innocent player character, and that person is given the option to report you as a murderer and place a bounty on your head. Kill five or more innocents in a short period of time, and your character is flagged a “murderer,” unable to use shops or access your bank account, and subject to being slain on sight by other adventurers who wish to collect the bounty on your head.

Ultima Online’s greatest strength is that it places administration of PvP entirely in the hands of its players, giving them an unrivaled sense that they, and not the Origin staff, control their world. The benefit of this feeling among players shouldn’t be underestimated; it’s a powerful contributor to a sense of immersion in the game environment. The system is weak, however, in controlling random aggression. Only after five reported kills does PvP activity have any real repercussions for the aggressor, and the game does little to track long-term aggressive behavior. If a player waits just eight hours of online time between murders, he can kill one player a day without ever reaching the murderer threshold. No penalty exists (other than being flagged a “criminal” for a short period of time) for attacking someone unless that person dies as a result of his or her injuries. Harassment attacks that fall short of a murder are still extremely common in Ultima Online. I was, for example, attacked by total strangers an average of once a day over three weeks of playing while writing this article, and killed three times. (Note to game designers: other game designers get really grumpy when your players kill them, especially when their colleagues make fun of their poor fighting skills.)

Player-toggled Flags (989 Studios’ Everquest) The developers of 989 Studio’s Everquest implemented a flagging system that will mark characters either as able to attack and be attacked by other players (+PK), or completely unable to engage in such activities (-PK). The method is a common one for controlling violence in small text-based MUDs, but my experience suggests that in a large-scale game, where the community is of sufficient size to allow true anonymity, the use of “throwaway” (also known as “mule”) troublemaker characters with -PK flags will abound. Such characters, immune from physical harm, can do many nonviolent but extremely annoying things to other players, such as following another character around wherever he goes, blocking entries to important areas, attacking monsters other players are already fighting, engaging in verbal harassment, holding goods stolen by +PK characters, running cons and scams, refusing to leave someone’s home, and more.

Brad McQuaid, Everquest’s producer, says his team is aware of the PK flag’s potential abuses and is prepared to combat them. The game will have a squelch command to combat verbal harassment, and out-of-context (non-role–played) harassment will result in punitive measures against the offender’s account. As for killing the creature another person is fighting, Brad says, “…the player or group that does the most damage to an NPC gets to loot it and receives the experience for the kill. This stops the jerk who comes along and gives the killing blow to a creature even though another person or group had engaged the NPC long before. He’s welcome to deliver the killing blow, but he will receive no experience for doing so.”

The general principle behind the Everquest kill-stealing prevention is sound, but what does one do about the high-level, -PK player who goes to a low-level hunting ground and steals kills repeatedly, doing more damage to creatures than the new players fighting them by virtue of an incredible advantage in skill? Does one block entry to such areas for high-level players? Does one prevent high-level players from attacking low-level monsters? Does one simply warn the player for disruption? The number of ways to get around the game design illustrates the greatest danger to the PK flag solution, namely that it creates an invulnerable subclass of character that players will be unable to police, thus shifting the burden (read: increasing staffing costs) to the game administrators. However, I suspect the flagging solution will be popular with a significant portion of Everquest’s customer base, because it allows responsible players who don’t enjoy PvP to play without interference from their more aggressive cohorts.

A Few General Guidelines

If the perfect solution has yet to be implemented, then what is the answer to managing PvP? A complete system design is beyond the scope of this article, but here a few things to be considered when designing an anti-PvP system.

Reduce overhead by minimizing staff intervention in player affairs. Minimizing staff intervention in player affairs is a principle that should be followed across all aspects of your game design, and it’s particularly true for your game’s PvP controls. Players will always exploit loopholes in your design to their advantage, and when they do, the best way to resolve the problem is to alter your code to prevent the undesired activity.

A good example of players using a system contrary to its intended design is the process by which a character of the cleric class may resurrect another character in Dragonrealms. When a character dies, a counter starts tracking skill loss, and the longer a character has been dead when resurrected, the larger the loss will be. Clerics are able to cast a Soul Bond spell that will neutralize this skill loss, and players generally expect that a cleric will do so before performing the resurrection. In the early implementation of this system, however, players used the process to force skill loss by intentionally resurrecting characters without first casting the Soul Bond spell.

Although the system mechanics allowed such activity, it didn’t fall within the behavior expected by the staff, and several clerics had their ability to cast the spell temporarily taken away for abusing the loophole before we coded changes to close it. Although our intervention took care of the immediate problem and made the victims of the aggression happy, it tended to make the players against whom we took action resentful. A pattern of such staff interference can result in an antagonistic relationship between your customers and staff and increased expenses to cover the lost development time spent correcting player behavior. It can also foster an environment in which players expect staff to handle their disputes, generating an ever-increasing number of assistance calls as your customer base grows. Whether you are willing to pay such costs is up to you.

Make all methods of PvP reportable to a hard-coded justice system. Players should be able to report all forms of PvP to the game’s justice system. Possible methods include presenting murder victims with a pop-up window, such as the one Ultima Online display, or allowing players to file complaints with NPC guards or magistrates. Whatever the reporting mechanism, it’s important to include all forms of PvP, such as theft, corpse looting, casting offensive spells, being harmed by an area-effect spell, being attacked with a weapon, being killed, or having player-controlled NPCs or creatures perform any of these offenses. The reporting mechanism should be intuitive and easily accessible, but should involve some effort on the part of the reporting player so only the truly important attacks are reported.

Extra care must be taken with area-effect spells. (Area-effect magic spells affect all characters within a certain radius of the character who cast the spell.) A common player-killer tactic in Ultima Online is to enter someone’s area-effect spell deliberately, then kill that person after the system flags them as “criminal” because of the damage the spell causes to the player-killer’s character. If you cannot detect such behavior with your code, possible solutions are either not to design such spells or to make them non-harmful to other player characters. You’ll lose a bit of realism, but the loss will be vastly offset by your closure of this common PvP loophole.

Another area of special attention should be your PvP theft-detection mechanism. Here’s an all-too-common scenario: Character A has a pocket full of coins, and encounters Character B. Character B steals the coins from Character A, but Character A fails his skill check to notice the theft attempt. The person playing Character A, however, notices the coins are gone, and draws the very reasonable conclusion that they were stolen by Character B. Under most game systems, however, Character A has no recourse, and will be labeled criminal if he attacks the thief in an attempt to recover the money. Such thefts are generally the most frustrating for your customers, because the person playing the thief will often use his immunity to taunt his victims. The solution is to allow the victim to report anyone to the justice system, with penalties for false accusations.

Make anti-PvP systems activate only upon player request. Only the victim of an online crime truly knows whether the actions against his or her character merit a reaction by the justice system. The person who harmed the character, for example, may be engaged in a friendly duel, or the violence may be a role-played conflict that the victim wishes to avenge personally.

Ultima Online has an excellent implementation of player-initiated justice, although it contains a few loopholes. If one attacks an innocent, for example, one is automatically flagged “criminal,” even if the attack were accidental or entirely consensual. A character of mine was once killed and looted by a stranger for being “gray” (indicating criminal status) after I accidentally hit a companion while in combat. My killer wasn’t impressed with my explanation, and I signed off that day much poorer than when I began. If I’d been murdered as “innocent,” however, I would have been able to report the attacker and place a bounty on his head.

Ultima Online also has a way to remove players entirely from the justice system if they are members of a player-run guild. The guildmaster of a guild may issue an official declaration of war on another guild, and if the declaration is reciprocated, the two guilds enter into a state of conflict in which members may attack, kill, steal from, and loot each other freely without becoming criminals. A second level of warfare offers even more uncontrolled PvP conflict. When a guild’s leader becomes famous enough, he or she is given the power to declare the guild an Order or Chaos guild. Upon doing so, the guild enters a state of perpetual warfare with all guilds of the opposing type, and members may fight with opposing guild members at any time, anywhere. “This provides the ‘ambush around every corner’ feeling that this type of player values,” says Raph. “The warfare system proved to be very popular, with 10 percent of guilds converting over to the ‘free-for-all’ guild type as soon as it became available.”

In Everquest, those characters who are flagged +PK will be able to attack and kill other +PK players at will, but a hard-coded race and alignment system will determine how the rest of the world reacts to the slaying. A player-character ogre, for example, is from a classically evil race. If that ogre kills a player-character elf, which is a classically good race, the ogre will, says Brad, “[when] he returns to his home town, be welcomed as a hero…. In this sense, player killing is encouraged in Everquest where it makes sense.” However, if elven guards observed the ogre attacking the elf, they would likely intervene. Furthermore, a character that kills members of his or her own race would eventually find NPCs of that race reacting poorly to the character.

Make revenge an option. This section merits an entire article in itself, so I‘ll mention it only for completeness and keep my comments brief. The key idea here is that many players would prefer to fight back when subjected to a PvP attack and wouldn’t enjoy reporting the activity to an NPC system. When a character is the subject of aggression, the aggressor should be flagged so the victim may fight back without penalty, whether it be an immediate response or a later ambush. Ultima Online has implemented this principle by flagging an aggressor attackable for two minutes per attack. My experience suggests that this isn’t enough time; for me, at least, my initial reaction to an attack was to flee to heal myself. By the time I’d recovered from the initial ambush, my aggressor was usually no longer eligible for a penalty-free attack.

Make PvP much less profitable than player-vs.-game activity. A certain percentage of those who kill or steal from other players do so simply because player-characters tend to be far more wealthy relative to the level of danger they present than NPCs or creatures. Take away the profit from PvP, and you’ll curtail a certain percentage of it. Ensure a stable supply of player-vs.-game activity, and you’ll decrease it even more.

The most obvious way to lessen the profitability of player-killing is to restrict looting of dead characters, without removing the ability for players to help their fallen comrades. One method is to prevent looting entirely, although a corresponding mechanism must be created to allow recovery of stolen items if a thief is tracked down and slain. Another is to allow looting only under specific circumstances. Ultima Online flags looters as criminals, making them vulnerable to attacks or having the NPC guards called to execute them.

Everquest had not yet finalized its corpse-looting restrictions at the time I wrote this article, but Brad says that the developers are considering several options. “…If you are -PK and you die, only you or someone to whom you give consent may loot your corpse. If you are +PK and come across the corpse of another +PK character, you currently are free to loot it. We are, however, experimenting with some limitations to make player killing more viable. We will test a system in which the killer may loot his victim only once, and may take only one item of choice from the corpse.”

If you implement such restrictions, provide enough monsters or NPCs to meet player demand, and give players enough wealth for them to feel they are making reasonable progress, you’ll drive player activity towards the monsters. Make your monsters and NPCs too poor, or fail to spawn enough of them, and your players will turn on each other. Similarly, it’s important to give player thieves enough creature or NPC targets to make the class economically viable, else a percentage of those who would normally only steal from non-players will turn to PvP stealing.

Restrict the ability of new characters to harm others. Players will always use system loopholes to maximize their gains, and if a new character is able to accomplish a highly dangerous task and realize the same gain as an older character, then the use of the aforementioned throwaway characters will abound. This is especially true when more than one character is available to the customer on the same account, or if free trial accounts are accessible to the players without the purchase of a retail product.

Stealing and scamming are the most common uses for throwaway characters, and is usually accomplished in a way that circumvents the system’s intended design. In Dragonrealms, for example, throwaways are frequently created to loot weapons dropped on the ground by dead adventurers. The throwaways then pass the weapons through friends and back to the main character on the thief’s account, disguising the true identity of the thief and making redress impossible. Throwaways also exploit loopholes in our player-to-player item exchange mechanisms, tricking adventurers out of their goods and then passing the profits to the real character on the account.

Simutronics is not alone in facing problems with throwaway characters. One common trick in Ultima Online used to be for two players to create thief characters, stand near a bank, and steal items from adventurers. If the victim detected the theft and called for the guards, the thief was executed. The thief’s partner would then lift the item from the dead body, and the original victim would have no way to get it back. Origin recently fixed this exploit by having the guards return stolen items to the victim if the thief were killed within city limits within two minutes of the theft.

Charge players for PvP activity in a currency that is valuable to them. When an activity has a perceived cost, the frequency of that activity will always decrease. It’s a basic supply-and-demand formula; make PvP more expensive, and fewer people will choose to purchase it. Those who choose to engage in PvP activities will therefore have to decide before every assault whether they are willing to pay the price. Scale the cost of that activity as its frequency increases, you’ll prevent repeated abuse by older, richer players.

You could, for example, make the tax a monetary one, and charge an aggressor 25 coins for his or her first reported murder, 50 for the next, then 200, 400, 800, and so on, allowing the character’s criminal past to decay one fine level per week if he or she refrains from all criminal activity. Characters who are unable to pay the fine could be restricted to a debtors’ area from which they couldn’t leave until they had performed enough low-paying menial tasks to pay off their debts. Preventing someone from leaving until their fines are paid would stop savvy players from offloading their valuables onto storage characters before going on a killing spree; allowing them to perform work to escape would prevent anyone but the worst cases from being trapped inside.

A tax doesn’t have to be a monetary one. A character could, for example, lose an increasing number of experience points or skills with each subsequent PvP report against him. If he or she reaches a certain threshold, that character would be hit with a curse that prevents all aggressive activity for extended periods of time. Another possibility would be to toss characters in a jail cell for increasing periods of time, where they must stay until their sentences are served.

Whatever you choose for your tax, the penalties should start at negligible levels and scale up exponentially rather than linearly. Low initial penalties, when combined with a slow decay of criminal histories, will allow new players to learn the system, allow all players to make the occasional mistake, and allow normally law-abiding characters to take the occasional swing at someone who really, really deserves it. Only those who try to make a career of harming other characters without their consent will be subject to heavy fines.

Balancing Good and Bad

There is no magic bullet solution to solve all of the PvP problems inherent to an online role-playing game community. No matter what methods one uses, players will always find ways to harass, pester, and annoy each other, so trying to eliminate all forms of aggression isn’t a realistic goal. If, however, you give proper reporting tools to the victims of non-consensual PvP, allow players outlets for consensual attacks, and make everything else costly, you’ll find the problems reduced to manageable levels. There is room for all styles of play in a properly designed role-playing game, and finding the correct balance is key.

Acknowledgements

I wish to extend a special thanks to Raph Koster and Teresa Potts of Origin Systems, and to Brad McQuaid of 989 Studios for their timely assistance. This article would not have been possible without them. Thanks also to Simutronics designer Emily Jacobson for her ruthless editing.

Derek Sanderson has held several design and customer service positions during his tenure with Simutronics, and has recently settled in as the company’s lead designer. He is currently pondering the career ramifications of commuting to work in a go-kart, and welcomes input on this subject at [email protected].