SINGAPORE—China has a new rule for the country’s hundreds of millions of young gamers: No online videogames during the school week, and one hour a day on Fridays, weekends and public holidays.

China on Monday issued strict new measures aimed at curbing what authorities describe as youth videogame addiction, which they blame for a host of societal ills, including distracting young people from school and family responsibilities.

The new regulation, unveiled by the National Press and Publication Administration, will ban minors, defined as those under 18 years of age, from playing online videogames entirely between Monday and Thursday. On the other three days of the week, and on public holidays, they will be only permitted to play between 8 p.m. and 9 p.m.

The government announcement said all online videogames will be required to connect to an “anti-addiction” system operated by the National Press and Publication Administration. The regulation, which takes effect on Wednesday, will require all users to register using their real names and government-issued identification documents.

Other details of enforcement weren’t made public, and phone calls to the National Press and Publication Administration went unanswered after business hours on Monday.