The US Department of Justice (DoJ) has charged five Chinese and two Malaysian men with hacking more than 100 companies.
The two Malaysian businessman "conspired" with two of the Chinese hackers to target the video games industry in particular, the DoJ said.
They would obtain in-game items and currencies by fraud, hacking or other means, and sell on the digital items for real money, it added.
Both Malaysian men have been arrested.
The five Chinese men were "fugitives" in China, the DoJ added. The US does not have an extradition treaty with China.
The other three Chinese hackers targeted software developers, computer makers, social media companies and others, the indictment said.
Two of the Chinese hackers - named as Zhang Haoran and Tan Dailin, both 35 - supplemented their attacks on technology firms with hacking video game companies.
It is alleged that the two Malaysian men - Wong Ong Hua, 46, and Ling Yang Ching, 32 - worked with the Chinese hackers to attack the video game firms in the US, France, Japan, Singapore, and South Korea.
"Several of the Chinese defendants compromised the networks of video game companies worldwide. That's a billion-dollar industry. And defrauded them of game resources," Deputy Attorney General Jeffrey Rosen told reporters.
"Two of the Chinese defendants stand accused with two of the Malaysian defendants of selling those resources on the black market through their illicit website."
At least nine known victim video game firms are listed in the indictment, but none are identified by name. Several are multinational firms, and at least one had multiple sub-companies.
Another of the indictments covered crimes including identity theft and money laundering by three of the Chinese men, which the DoJ said had affected more than 100 companies.
It said that Jiang Lizhi, 35, Qian Chuan, 39, and Fu Qiang, 37, worked as senior managers for a Chinese network security company.
But they also used their skills for "offensive" operations, it added.
The companies were located worldwide - not only in the US but also Australia, Brazil, Chile, India, Japan, Singapore, and elsewhere.
Microsoft, as well as Google, Facebook and Verizon all aided officials in the investigation and in cutting off the attack methods, the US government said.
Mr Rosen also blamed the Chinese state for allowing such activity to happen.
"The Department of Justice has used every tool available to disrupt the illegal computer intrusions and cyber-attacks by these Chinese citizens," he said.
"Regrettably, the Chinese Communist Party has chosen a different path of making China safe for cybercriminals so long as they attack computers outside China and steal intellectual property helpful to China."