Kill stealing

Kill stealing, sometimes abbreviated to KS, is a video game term which describes when a player is about to defeat an opponent, but another player defeats it instead, thereby gaining the reward for killing it despite the other player having done most of the work. Players do not appreciate having their hard work awarded to other players, so kill stealing is looked down upon. Despite that fact, it was quite rampant in many early MMO RPGs and players demanded game designers implement ways to prevent it.

Methods of prevention

Here I discuss several methods developers have come up with to discourage or prevent kill stealing.

Divide the reward evenly

Instead of giving all of the reward to the player who defeated the enemy, the reward is divided up evenly among everyone who was engaged in the battle. Using this method, a kill stealer won't get as much of a reward, and the player they steal from won't lose as much. However, the kill stealer will still receive the same reward for considerably less work, so, while it may reduce kill stealing, it certainly won't eliminate it.

Divide the reward relative to damage

In order to help eliminate the unfair way in which rewards are divvied up, this method also divides the spoils, but they are divided relative to how much damage each player does to the enemy. In the case of kill stealing, the original player often does 95% of the damage with the kill stealer doing the last 5%, so the original player will get 95% of the reward. To implement this method, the game must keep track of how much damage each player does to the enemy in order to divide it properly. In this case, kill stealing is still possible, but the reward is befitting the work, so the only thing a player will be out is the psychological satisfaction of landing the killing blow.

However, the method introduces a new problem. It's common in MMOs for players to have specific roles in combat, like tanks doing and taking much of the damage, and healers healing them. In this method, healers, who rarely damage the monsters, get very little reward despite playing a necessary role. When the reward is divided evenly, they would still get their share, even if they never landed a hit on the enemy, but, using this method, they could receive nothing.

Divide the reward relative to effort

In this method, when an enemy is defeated, each player who was involved in the combat receives a reward relative to the amount of effort they put forth. This includes the players who directly damaged the enemy, but also any assisting players who healed or buffed anyone involved in the combat.

This method has the benefit of dividing the reward evenly while also encouraging cooperative play. However, the down side is that it's more difficult to implement, and even harder to balance. It raises all sorts of questions like, how much reward should someone get for healing compared to doing damage? How much is a dexterity buff worth? How do you reward a character that draws aggro to keep others safe? What if players don't want help from outsiders who give them unhelpful buffs in order to take their experience?

Everyone gets all the reward

Rather than divide the reward, this method gives the full reward to everyone involved in the battle. For example, assume a goblin rewards 100 gold pieces when a single player kills it. When two players band together to kill the goblin, they are not rewarded 50 gold pieces each, but 100 each, and, when 10 players gang up and kill a goblin, they don't get 10 gold pieces each, but still 100 each. Obviously, this method doesn't make sense in the game world (it implies that enemies magically acquire more rewards based on how many people collectively kill them), but it does make kill stealing pointless. And, rather than discourage cooperative play, it greatly encourages it.

This method is easy to implement and is used in Realm of the Mad God. It does create a significant downside however. Since reward is increased based on the number of players involved in combat, players are encouraged to form enormous roving swarms and rapidly wipe out enemies causing all the players to very rapidly gain rewards.

Claiming enemies

The first player to engage in combat with the enemy is the only one who can receive the rewards for the monsters. This method greatly reduces kill stealing because another player cannot gain anything by engaging with an enemy that has already been claimed. This method is also pretty easy to implement. When a player begins combat with an unclaimed enemy, they claim it. If the player's character dies in combat or runs away, the enemy returns to an unclaimed state. The major downside of this method is that is discourages cooperation, after all, what's the point of helping someone defeat and enemy when they won't gain anything from it? A secondary downside is, it doesn't make sense thematically.

Claiming enemies with teams

This is similar to the claiming enemies method, however, in order to encourage cooperation, players are allowed to team up. Once a player claims an enemy, only those people who they allow to help them may also attack the enemy, and thereby receive the reward. The division of the reward can follow any of the forms in the methods above.

Implementing this method isn't very difficult. But the way in which players can join and leave teams would have to be determined. Players could ask to join the team of another player, and they other player would have to allow it. But players must also be able to leave teams they joined, and players who allowed teams would have to be allowed to boot other players from them. And this creates a few caveats. What do you do when a player leaves the team during the combat? What about players who are booted from the team? Do they still get a share of the reward? If not, this would allow for a reverse kill steal where a player claims an enemy for their team and, just before the enemy is defeated, boots the entire team and receives the entire reward on their own!

Give rewards during combat

Instead of giving a large reward at the end of combat, the game could give smaller rewards all throughout the combat encounter. There is little point in kill stealing if the player who started the combat already has most of the reward. For example, the game could award experience for each point of damage done.

The game Ultima Online implements this method for experience. Instead of rewarding the player with experience for killing an enemy, the skill statistics of the player's character are increased for being involved in combat. Getting hit, doing damage, fighting multiple enemies at once, all of these things increase the player's skill, and, the longer the player remains in combat, the more skill they gain. In this case, delivering a final blow doesn't give anything special.

The downside of this method is that it's harder to implement compared to the traditional style of giving a reward simply upon killing an enemy. It also creates an unusual side-effect where players are encouraged to heal their opponents in order to prolong combat and gain more reward.

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