> You can still inject your hack via LD_PRELOAD + detouring dlsym/dlopen. Even were that not possible, you could have fun with, e.g., ptrace.

This all works on Windows, too. It's what things like FRAPS use, or the half dozen game overlays that apps like Mumble offer (including Steam's for that matter)

Anti-cheat systems are just a constantly escalating game of cat & mouse like anti-virus systems where signatures and code patterns are recognized, game DLLs are hashed to see if they were modified, etc... There's zero, zilch, nada OS level support for these.

Is there even an expectation that anti-cheat utilities can work? They're worse than DRM - unless the anti-cheat software is certified and your system can do hardware trusted execution, it's going to be worked around. (it's most likely also possible in case of trusted execution...)

They do have some limited success at deterring "script kiddies" and similar, however I think that this is far more difficult to do on Linux than Windows. Back when there were a few games around on Linux that used PunkBuster (America's Army, Enemy Territory), PB offered almost no real protection and, e.g., ET's mod developers decided to build in some anti cheat protection of their own into the mods which was superior to PB's. (Which, of course, also got bypassed eventually)

exactly the same sort of tricks are possible on windows via debugging hooks and process injection. I don't see how Linux is any more problematic on this front.

Windows is closed source and offers some pseudo-"security" through that. Also, you can't just modify the kernel to suit your needs...

You can however load kernel drivers on windows and achieve pretty much the same thing.