A group of about 600 Activision employees officially unionized Monday, joining the Communications Workers of America and creating the largest union of gaming studio workers in the country, officials announced.

The group is the first group to unionize since Microsoft bought Activision, and 344 of those workers are in Eden Prairie.

The group includes 344 quality assurance workers in Eden Prairie, plus others in Austin, Texas, and El Segundo, Calif., and increases the number of unionized video game workers within Microsoft to 1,000.

Microsoft's gaming bought Activision Blizzard for about $69 billion in October after a bruising, yearlong regulatory battle mainly over anti-trust concerns.

In an effort to assuage concerns, Microsoft signed a neutrality labor agreement, saying it would not express any opinion should workers decide to unionize in the future. The agreement helped seal the deal. The mega acquisition went forward, adding gaming fan favorites such as Candy Crush, Call of Duty Mobile and World of Warcraft to Microsoft's video and cell gaming arsenal.

The purchase instantly made Microsoft the third-largest gaming company by revenue in the world.

Monday's announcement marks the first union expansion under the neutrality agreement. The workers join several hundred Microsoft ZeniMax studio workers in Texas and Maryland who joined the CWA in January 2023.

While the union gains are significant, they reach just a fraction of Microsoft's gaming staff, which totals nearly 10,000.

Still, the new union alliances come at the same time Microsoft is making its Activision, Blizzard and King games available on various platforms including the XBox Game Pass.

Union members noted that the quality assurance jobs affected by the CWA alliance tend to be among the lowest paid jobs in the gaming industry, so a union alliance should help.

"We wanted to see improvements in the workplace, including higher wages and getting more career opportunities and so we're eager to unionize," Kara Fannon, a Microsoft quality assurance game tester in Eden Prairie, said in a statement. "We're ready to grow our careers here, and believe that having a strong union contract will set workers and the company up for success."

Amy Pannoni, Microsoft's deputy general counsel, said the company looks forward "to continuing our positive labor management relationship."

This story contains material from the New York Times.