I have no idea if the gamers installing it are “unaware” (I never played such a game), however it’s still a shitty practice. The average Joe has no idea what the hell a rootkit is and it’s predatory to exploit this. Also, no game should install rootkits. For the love of god, it’s a videogame.

most anticheats run in the kernel, even the most popular ones like battleye and vanguard.
also they are often installed automatically while launching games for the first time, without any prompts