The video game Counter-Strike: Global Offensive pits players against each other in a world of bomb-making and hostage-taking. And until this week, the game was host to a real-life crime ring: virtually all in-game micropayments were being used to launder money.

Normally, Counter-Strike players can buy what are known as in-game keys to open boxes full of supplies. The game lets players trade items, leading to an online market for rare keys. But that virtual market has been flooded by frauds trying to move dirty money, gamemaker Valve said.

“Worldwide fraud networks have recently shifted to using CS:GO keys to liquidate their gains,” Valve announced in an update this week.

And like a playground bully hogging the kickball, these crime rings have gone and ruined key-trading privileges for everyone.

“Nearly all key purchases that end up being traded or sold on the marketplace are believed to be fraud-sourced,” Valve said. “As a result we have decided that newly purchased keys will not be tradeable or marketable.”

In-game microtransactions have been a running headache for everyone from game manufacturers to regulators to concerned parents who liken them to gambling. A whole genre of YouTube tutorials promises big winnings to players who participate in online marketplaces for in-game items, sometimes resulting in scams. The Federal Trade Commission previously fined two popular YouTubers who encouraged viewers to sell items through the website CSGO [Counter-Strike: Global Offensive] Lotto. The YouTubers were secretly investors in the site.

The wildly popular game Fortnite is also ripe for fraud, a January report found. Cyber-criminals allegedly stole credit cards, then used them to buy in-game money, which they sold at a discount on the dark web. The game could also be used to scam money from unsuspecting players. One popular scam promised cheap in-game money in an attempt to learn players’ credit card details. Fortnite’s large audience with children meant an ocean of easy targets, Slate noted at the time.

Sometimes the schemes transcend simple credit card theft. Games like World of Warcraft are notorious for “gold farming,” a dubious industry in which players put in long hours earning in-game money, then sell it for real money to wealthier players who want to save time. The practice is especially popular in China. 

But not all the Chinese gold farming has been voluntary. A 2011 Guardian report revealed that prisoners in labor camps were being forced to generate World of Warcraft gold, which was then sold for real money internationally. One prisoner interviewed said he was forced to break rocks all day and play World of Warcraft all night.

“If I couldn't complete my work quota, they would punish me physically,” he said. “They would make me stand with my hands raised in the air and after I returned to my dormitory they would beat me with plastic pipes. We kept playing until we could barely see things.”