Catch Cheaters

A cheater in a MMOG does not just cheat himself. He performs an injustice to all honest players. Cheating short-circuits gameplay, so it achieves exceptionally high performance. Players adopt high performance strategies, whether intended by the designers or not. Cheating also penalizes the relative performance of all non-cheaters. If not corrected quickly, cheating will spread like wildfire. In a matter of weeks or even days a cheat can flood the game's economy. These techniques can help catch cheating before it ruins the economy.

Start at the table that preprocessing generated. This lists each character ID and their performance. Sort the list by the performance column. Now, at the top of the list is the most suspicious character ID. Investigate his exceptional performance.

	Investigate suspicious player performance starting at the top.

Let's sort the example table by the EPH column. The character at the top is the most suspicious. Even though he has a lower total experience gain, he has a higher rate, since he accumulated the experience during fewer hours. Investigate the logs to discover how he performed so well. The answer will enlighten you as to how players use and abuse your game.

The answer does not indicate the player's intention. The player may have been using a legitimate feature of the game. In fact, a player may argue that unless he modified the software, all of his behavior is a legitimate use. He played the game as it was given to him. Regardless of the motive, deleting a cheater cannot solve the problem. System imbalances breed cheaters, so the design itself can prevent cheating.

Cut Production Costs

Each game asset took some amount of programming, art, design, testing, and customer service to develop and maintain. Yet some of these classes, items, monsters, quests, skills, zones, and other objects in your game are being wasted. This lowers developer morale.

Game assets with low performance have a return-on-investment value that approaches zero. Players make decisions and optimize their decisions over time, and communication among players accelerates the migration to an optimal strategy. They quickly adopt the highest performing game assets available, and discard low-performance assets. In terms of competition, these assets are liabilities, so they become obsolete. For an obvious example, if there are two nearly equivalent weapons, except one has a higher damage rate, the other weapon is obsolete. In a game, this kind of decision, between obsolete assets and newer assets creates "fat"; there is some fraction of your game that might as well not exist, because no one uses it. Imagine having to break this news to an artist: "Thank you for the long-nights you spent making this new graveyard that we specified, but no one hunts there. Sorry about that."

	Are players using all of your game's assets? (Nexon's Dark Ages)

It does not have to be this way. A wise patch can put the assets back into the players' list of options. Recycle the artists, programmers, and testers' hard work as much as possible. Create new, well-balanced instances. Measure and prove their balance in terms of performance. Do not change the values of existing instances. Let them remain as they are. Recycle the art with modest modifications so those man-hours are not lost. But only recycle obsolete assets. Players do not tolerate recycling of assets that they do not consider obsolete. They demand fresh assets.

Increase Customer Renewal

If the player cannot or does not realize how to improve his performance with the choices he has already made, he is doomed. For example, if all high-level fighters perform worse than average high-level characters, all fighters are doomed. The players' sense of doom will become the developer's death knell unless you act fast.

	If a player cannot improve her performance you may lose her.

When a player suffers from poor performance in a single-player game, he suffers alone. But in a massive multiplayer game, his whole team suffers. Unfortunately, a good choice for the team to increase their performance is to exclude low-performers. When low-performance is not the player's fault, this breeds frustration. Suppose a group of players can increase its EPH 20% by excluding low-performance players. Sadly, many groups will. Suppose the excluded low-performer is unable to alter his EPH liability. Like an endangered species that is unfit to hunt and unable to evolve, this set of players becomes extinct. The character will not only become extinct from the playscape, but the player's motivation to play will become extinct, too. If she will not play, eventually she will not pay, either.

To prevent this, balance the strategies. Do not edit existing instances of game assets. This will upset other players using other strategies. They will perceive the correction as an injustice, an act of favoritism. Instead of creating a perceived injustice, add new assets.

If your game is commercial, improve player performance instead of worsening it. If some asset is too good, but players love it, let it be. Only when the asset would cause long-term customer losses should it be removed, because removing or degrading an asset decreases customers' good faith. There are few things that say, "I do not want your money, go away" as quickly as removing a beloved feature in the game. Players paid money in advance and continue to pay a subscription fee each month for a reason. They expect the game to improve each month. Their criterion is simple. The game should improve for their character personally and for the special interest group that their character belongs to.

A major error's existence costs more than this loss of good faith. In these uncomfortable cases, prove to players you care by negotiation and diplomacy.

Imagine a worst-case scenario from the most extreme player's perspective: This morning your paycheck was suddenly slashed 50%. Your brand of car drove half as fast, required repairs twice as often, and costs twice as much. Because the "gods" said so. Some customers take the game just as seriously.

Go Forth And Mine!

We have only touched the tip of the iceberg of data mining and game design. Both are elaborate and exciting fields for research, experimentation, and application. For years, we game designers have wanted systematic and scientific tools, and I hope that data mining is one such tool to help improve your game's design. If you have questions, comments, or would like to discuss this topic in detail please contact me at kennerly@sfsu.edu.

Acknowledgements

I could not have written this article without the support of each of Nexon's employees and players. They encouraged my experiments.

Further Reading

Han, Jiawei and Micheline Kamber. Data Mining: Concepts and Techniques. Morgan Kaufmann Publishers: San Francisco, 2001.

An introductory practical explanation for database programmers.

Hand, David, Heikki Mannila, and Padhraic Smyth. Principles of Data Mining. MIT Press: Cambridge, 2001.

An interdisciplinary explanation of the mathematics and fundamentals of data mining.

Electronic Privacy Information Center. "Total Information Awareness (TIA)" April 20, 2003