(Reuters) – China is reviewing new games to ensure they meet stricter criteria for content and protection of children, Bloomberg News said on Thursday, citing people familiar with the matter.

The media watchdog is re-evaluating titles submitted for approval by game developers from Tencent Holdings (OTC:) Ltd to Netease Inc to make sure they comply with fresh curbs imposed in August, the report https://bloom.bg/3hEq8ix said.

Tencent refused to comment, while Netease declined to respond immediately to Reuters’ request.

China banned video gaming for children under 18 years old last month. This was a strict rule meant to stop a rising addiction to “spiritual opioid”.

The report stated that the National Press and Publications Administration asked developers late in August to resubmit titles according to the new guidelines.

It said that regulators are cracking down against increasingly popular games featuring zombies, which are “too frightening” according to NPPA standards.

Scrutiny was also stepped up on subjects regulators consider undesirable, such as “boys’ love” themes that have recently become trendy, it said.

China is tightening its controls after years of rapid growth and has reacted to a variety of sectors, from technology to education and property.