Comment by Draiken
Most game studios pay someone else to make the anti-cheats and many already have Linux versions that the studios choose to not enable.
Besides, if your anti-cheat only ever looks at the system level, it'll easily be bypassed by hardware cheats. At some point I think anti-cheats will have to "know" the game to be able to detect anomalies. It's the only way to effectively stop many categories of cheats.
Those Linux versions are generally not kernel-level. Do you know of any that are?
And yes, of course it's not fool-proof. It's not supposed to be. It's about probabilities: for a given online game, what is the chance that I end up in a match with someone who is obviously cheating and using that to ruin the game for everyone else? The harder you make cheating, the lower that is.