Ahead of its official debut this year, the biggest gaming company on the planet has enlisted Chinese police to root out the underground rings that make and sell cheat software. It’s helped law enforcement agents uncover at least 30 cases and arrest 120 people suspected of designing programs that confer unfair advantages from X-Ray vision (see-through walls) to auto-targeting (uncannily accurate snipers). Those convicted in the past have done jail time.

Tencent and game developer Bluehole Inc. have a lot riding on cleaning things up for China, which accounted for more than half the game’s 27 million users, according to online tracker Steam Spy. It’s also the biggest source of cheat software, undermining a Battle Royale-style phenom that shattered gaming records in 2017 and surpassed best-sellers like Grand Theft Auto V. The proliferation of shenanigans threatens to drive away first-time users vital to its longer-term growth.

Yet they continue to thrive. The game’s message boards are riddled with complaints about mysteriously indestructible opponents. Software rings ingeniously treat its league tables like free ad space: as of Tuesday, eight of PUBG’s top 10 players bear names such as “contact QQ574352672,” ironically a private account on Tencent’s own QQ messaging service through which enterprising players can procure cheat software. One vendor offered a 100 yuan ($15) program called “Jue Ying” or extreme shadow that, among other things, obscures players and grants a birds-eye view of the battleground. Another QQ dealer sent notices to customers warning them to “maintain control and keep your kills within 15 people per game,” presumably to avoid detection.

“PUBG is going through a puberty of sorts and cheaters threaten to stunt its growth,” said Kim Hak-joon, who analyzes gaming stocks for South Korea’s Kiwoom Securities Co. “Cheaters mostly drive away new users, and without retaining new users, PUBG won’t be able to consolidate its early success and become a long-lasting hit.”