Four weeks after Chinese regulators first denounced video games as "spiritual opium" and identified "video game addiction" as a widespread phenomenon distracting young people from their responsibilities, authorities on Monday announced they would restrict the hours during which Chinese minors are allowed to play. From here on out, gaming during the week will be banned. On Friday evenings, as well as during holidays and Saturdays and Sundays, gamers will only be allowed to play during a single hour between 2000 to 2100 local time.

Already, Monday's new rules are impacting shares of China's online gaming companies. Shares of a swath of companies, including Tencent, NetEase, Bilibili, Kingsoft Cloud, Huya and Sohu.com, tumbled during Asian trading.