> Or your game design might require you to hear sounds on the other side of the wall (footsteps, gunshots, etc.) which allows cheats to infer what what may be behind the wall better than a person would.

Yes, and you cannot prevent this except in in-person tournament.

Any output send toward the player, even a faint audio queue could be analyzed, and use to trigger an action or display an overlay to the screen, and no amount of kernel-level stuff will prevent that, as you can do this outside of the computer running the game.