Diablo III isn’t exactly an MMO, but it still suffers from some MMO-style problems. For example, Blizzard has recently banned several thousand players that were using bots. Bot software can automatically control your character when you’re away from the computer via the use of a very rudimentary A.I. scheme. This allows you to level up your character and earn gold and loot without actually playing the game. Simply leave this on while you’re at work and come home to an ultra-powered character with no effort required.
"In addition to undermining the spirit of fair play, botting, hacking, and other forms of cheating can also cause technical problems with the game as well as contribute to performance issues with the Battle.net service," a Blizzard community manager said.
Blizzard urges any user who notices a hack or bot being used to report it. Additionally, an upcoming patch for Diablo III will allow users to report bad behavior directly through an in-game client.