Beijing is starting a special investigative campaign into online video games to root out those with “low taste,” the official Xinhua News Agency reported.

The monthlong campaign, which began Monday, will seek to identify games that “have severe deviation in value, distort history, smear historical figures, violate government policies on ethnicities and religions, promote content that are lurid, violent or related to gambling,” Xinhua said.

China’s booming video game market, the world’s largest, is being driven by game developers like Tencent and NetEase.

The Chinese government has a tight grip on content distributed in the country, including movies, music and video games.

Last year, Tencent had to change a popular battle royale-style game that the regulator said was too gory and violent and bring it closer in lines with “socialist core values” before being allowed to release it in China.

The Xinhua report did not identify any games or companies. It also said authorities would block any illegal content that originate from overseas and violates Chinese law.