Roco Kingdom 4, adapted from a popular Web game, hit Chinese mainland theaters on Aug 13. [Photo provided to China Daily]

Gamers' response during online play, such as brain waves and blood pressure, were also applied to the production process to see if audiences will be as excited with the movie.

Three sneak previews in Shenzhen, Guangdong province, and Shanghai that collected responses from more than 100 families, made Tencent spend another three months on revising an almost-finished movie.

A 280-member team led by Canadian director Hugues Martel, known for the Oscar-nominated The Triplets of Belleville, spent 19 months on producing Roco Kingdom 4.

The Quebec-born animator moved to China about 15 years ago and now has his own company based in Shanghai. He speaks fluent Mandarin.

Roco 4's supernatural protagonist, Matthieu, a green-skin elf who can give life to the dead, is named after Martel's 2-year-old son.

Living in a foreign country for a long time, Martel says that the movie's Matthieu embedded with his own nostalgia of family and motherland.