In practice, client side anti cheat is essentially DOA because hardware cheats that analyse the player's screen on a 2nd computer and proxy inputs to your mouse USB have made it so cheat clients are never actually executing code on the host machine.

At that point, even players cant tell someone is cheating because the cheats aren't modifying the game state in a noticeable way- they're still weak to effects that obscure your vision and have inputs that are difficult to differentiate from a "real" player.

IMO cheating is a social problem and one that is totally impossible to beat with rootkits by design.