On Monday, China’s National Press and Publication Administration published new rules on playing video games. Kids and teens below the age of 18 can only play online video game for up to three hours per week on Friday, Saturday and Sunday. This year gaming giants such as Tencent and NetEase have faced a host of regulatory challenges and this is the latest one.

A translated notice of the new rules stated that people under the age of 18 would be allowed to play video games for one hour between 8 p.m. and 9 p.m. on weekends and legal holidays. According to the agency, these rules have been enforced in order to safeguard the physical and mental health of children.

Companies providing online game services to minors have to follow the rules. They have to limit the ability to serve this group of users outside the mentioned hours. They have to provide services to those who have logged in with real name registrations. So, the gaming companies cannot remain ignorant about the background of their users.

The 2019 rules had given this age group longer gaming hours. They were allowed to play up to 90 minutes on weekdays and three hours on Saturday and Sunday according to a report by the New York Times.

Gaming has been a fast growing and profitable sector in the internet industry in China. Earlier, Tencent had reported that only a small portion of their earnings are obtained from younger players in China. The company reported that 2.6 percent of its gross income in Q-2 was from players who were under 16.

In July, Tencent began facial recognition for gamers to verify their age. They are scanned to confirm whether they are adults. The gaming giant confirmed its support to the new rules and said that it would implement them. The company had spoken of proposed new rules in gaming and mentioned that it would be compliant.

NetEase, another gaming giant in China saw it shares fall in the U.S. by four percent on Monday. The company was unavailable for comment when contacted by CNBC.