The World of Warcraft GameMakers Guild, created with help from the Communication Workers of America (CWA), includes employees from all departments, such as designers, engineers, artists, and producers.

Together, they have formed the largest union at Microsoft, which includes multiple departments and disciplines.

This news comes less than a week after the formation of the Bethesda Game Studios union, the largest union at Microsoft at its announcement.

The World of Warcraft GameMakers Guild has over 500 members across Blizzard offices in California and Massachusetts.

Despite its size—it is the second largest union at Microsoft overall, behind Activision's 600-member QA union—Paul Cox, senior quest designer and Blizzard veteran, said that Microsoft's labour neutrality agreement helped get the organisation started.

Microsoft spokesperson Delaney Simmons said: "We continue to support our employees' right to choose how they are represented in the workplace, and we will engage in good faith negotiations with the CWA as we work towards a collective bargaining agreement."