The UK’s competition regulator has rejected Microsoft’s proposed takeover of Activision Blizzard, a leading video game developer famous for titles such as Call of Duty, citing concerns about its potential impact on the cloud gaming market.

This would have been the largest acquisition in gaming history, with a value of $68.7bn (£55bn). By combining Activision’s “AAA” titles such as World of Warcraft, Hearthstone, Candy Crush Saga, and Overwatch with Microsoft’s first-party developers, Xbox consoles, and control of PC gaming, a powerful gaming entity would have been created.

Despite Microsoft’s announcement that Call of Duty would be available on other platforms for at least a decade, which the regulator believed preserved competition in the home console market, the regulator still blocked the deal. Sony, the owner of PlayStation, had protested against it.