The Chinese source says 追求血腥, which I'd translate poetically as "pursue the smell of blood". So there wouldn't have to be any blood visible on screen, as long as you can "smell"/imagine it. Essentially "overly violent", as you guessed.

This is really targeted at China's domestic game industry and various tendencies the Party disapproves of because they believe those games to "corrupt the youth" or something like that. The leadership is full of very conservative people for whom a chainmail bikini verges on pornography.