The Chinese government has banned under-18s from playing online games for more than an hour a day, and then only between 8pm and 9pm on Friday, Saturday, Sunday and public holidays.
The ban will be enforced by online gaming companies which are now required to strictly enforce rules requiring users to register accounts with their real identities in order to play.
The new restrictions were announced on the Chinese social media platform Weibo by The People's Daily - the official newspaper of the Chinese Communist Party - and came from General Administration of Press and Publication.
It follows shares in China's biggest online gaming companies slumping after state media branded their products "spiritual opium" and compared them to "electronic drugs" earlier this month.
The reference to opium is charged in China, where European powers, including Great Britain and France, hobbled the Qing dynasty in the mid-19th century through heavy imports of the drug, ultimately leading to Hong Kong being given to Britain as a sovereign territory before it was returned in 1997.
The crackdown on gaming companies was sparked by an article published by the state-run Economic Information Daily that warned teenagers were addicted to online video games and called for the industry to be curbed.
The newspaper particularly appeared to criticise Tencent's flagship game Honour Of Kings, which it is reported is sometimes played by students for up to eight hours a day.
"No industry, no sport, can be allowed to develop in a way that will destroy a generation," the newspaper wrote, comparing online video games to "electronic drugs".
The newspaper called for "mandatory means" to force online gaming companies to prevent addiction among young players.
Tencent - which was behind the development of the latest Pokemon game released last month - responded by saying it would introduce new measures to limit access to its games and the time spent on them by children.
Following that criticism Tencent imposed restrictions on its Honour of Kings game, limiting under-18s to playing only an hour a day normally and two hours a day on holidays, but the new edict from the General Administration of Press and Publication goes much further.