The PlayStation 4 launched in China back in March, but sales haven't been as strong as Sony would have hoped. PlayStation boss Andrew House said in an interview at the Tokyo Game Show this week that China's censorship rules are hurting the sales potential of the PS4 in the country.

　　"We are still challenged somewhat with a censorship regime that we have to work with," House told Reuters. "This can be time-consuming."

　　Despite a slow start, House said he still sees huge potential in the China, a country whose gamer population exceeds the entire US population.

　　"I don't think it has been a kind of a rocket launch start," House said, adding that he envisions "tremendous potential for gaming as an entertainment medium in China." With an estimated population of 1.35 billion and a growing middle-class, China is considered to potentially be the world's largest market for video games.

　　According to China's censorship rules, nothing that promotes drug use of violence is allowed. All games must be approved by the Shanghai government culture department and the approval process for games is said to take no longer than 20 days. A full list of content that is not allowed in games sold in China is available here.

　　The Xbox One launched in China in September 2014 and sold around 100,000 units during its launch week. Nintendo has not yet announced specific plans to bring its consoles or games to the market.

　　According to one Asia business analyst group, the PS4 and Xbox One systems in China may only sell fewer than 550,000 units, combined, in 2015.