Software maker Blizzard, maker of the hugely successful Warcraft video game series, is engaged in a legal dispute with a programmer who has created a tool that automates actions inside of one of its popular games.

Blizzard's parent company, Vivendi, has filed suit against Michael Donnelly over a bot the programmer made that operates inside of the World of Warcraft (WoW) massive multiplayer online game (MMO). The tool, which the reportedly has sold 100,000 copies, gives gamers an edge by allowing their characters to perform actions, even when the gamer is away.

The company contends that the program, dubbed MMO Glider, infringes upon the title's copyrights and degrades the game for other players.

Blizzard's designs expectations are frustrated, and resources are allocated unevenly, when bots are introduced into the WoW universe, because bots spend far more time in-game than an ordinary player would and consume resources the entire time, Blizzard stated to a U.S court.

Representatives of the firm, including a private investigator, came to Donnelly's home prior to the formal legal action, threatening him and ordering him to stop distribution of the tool. The actions offended the programmer, according to his legal submissions.

When they arrived, they presented Donnelly with a copy of a complaint that they indicated would be filed the next day in the US District Court for the Central District of California if Donnelly did not immediately agree to stop selling Glider and return all profits that he made from Glider sales, his lawyers stated.

Donnelly argues that his software stays within the bounds of the law, but Blizzard believes because the software copies the game into computer memory, the title's End User Agreement was broken.

Both sides have submitted legal summaries to a court in Arizona and are awaiting judgment in the case.