Chinese inmates in Jixi labor camp are reportedly forced to slay demons, battle goblins and cast spells in online games to farm credits for prison guards who trade virtual currencies for real money.

A former prison guard turned inmate, told The Guardian that the operation was even more lucrative than the physical labor that prisoners were also forced to do. He shares:

“There were 300 prisoners forced to play games. We worked 12-hour shifts in the camp. I heard them say they could earn 5,000-6,000rmb [US $770-$925] a day. We didn’t see any of the money. The computers were never turned off.”

He adds that the inmates were kept playing until they could barely see things and missing the daily quota would result in physical punishment and abuse.

It is a phenomenon known as “gold farming,” the monotonous repetition of basic tasks in online games such as World of Warcraft to build up online credits, which millions of gamers around the world are prepared to pay real money for.

The trading of virtual currencies in multiplayer games has become so rampant in China that it is increasingly difficult to regulate. This exploitation of prisoners is a clear example of such.

It is estimated that 80% of all gold farmers are in China, the world’s largest Internet population. There are thought to be 100,000 full-time gold farmers in the country, which doesn’t come as a surprise given that the pay is actually better than what they would get for working in a factory.