On the top floor of a trendy anime-themed mall near Beijing’s Chaoyang Park, a three-minute trailer gave a taste of what is expected to be China’s next blockbuster role-playing video game. On the large screen, characters called Eastern Heretic, Western Venom, Southern Emperor and Northern Beggar appeared in exquisitely rendered martial arts duels. Rising above it all with a sinister smile was Dongfang Bubai, a martial artist who castrated himself to learn the secrets of the skills in the...