One player commented," I learned a lot from playing the game, including how the virus spreads and the measures that can be taken to better prevent and contain the epidemic."

Amid a surge in players, Ndemic Creations has reminded them that Plague Inc. is not a "scientific model" and that people wanting information on the outbreak should obtain it from health authorities.

"Many students played the game over the extended Spring Festival break," said Li Ding, a college teacher in Shenyang, Liaoning province, adding that she spent more than five hours on the internet each day.

In an attempt to stop large numbers of people gathering, officials have banned outdoor games of mahjong, chess and cards and have used drones for virus patrols. As a result, demand for online games has surged.

According to online data service provider Qimai Technology, since Jan 27, Tencent's Happy Mahjong has remained in top place in the download rankings for chess and card games, followed by Fight the Landlord, a card game also developed by Tencent.

An ad from the company reads: "Less outings, more company. Join us and play mahjong and cards with friends at home."

To attract users, special free online rooms opened for Happy Mahjong and Fight the Landlord from Feb 1 to Feb 9.

Zhao Kun, a Shanghai insurance agent, said: "My screen time recently has exceeded 12 hours a day. There's nothing I can do, but play games, binge-watch and surf the internet."