They're usually rootkits that are auto-installed by the game. They end up in Services and while they typically don't auto-start (i.e. the game starts the servic

They're usually rootkits that are auto-installed by the game. They end up in Services and while they typically don't auto-start (i.e. the game starts the service and stops it at shutdown) they basically have full kernel-mode access to your PC for the stated purpose of "catching cheaters" In the past these anti-cheat modules have caused compatibility issues or had security vulnerabilities, which is fun. DRM packages tended to be similar. If I check my Services pane right now, I have Easy Anti-Cheat and BattlEye listed which are both anti-cheat services installed by steam/etc video games that run with System level permissions. IIRC PunkBuster also uses a system service. Because these are system services, they stay installed even after you remove the game. There are ways to manually remove them of course but the moment you launch a game that uses them, they'll get reinstalled.