The place to begin that study and establish exactly what control systems are present and how they work is in studies like the one that you dismissed as a trivial game.

Telling a person "Perform this task, which involves acting like a control system" and discovering that people can, indeed, act like a control system doesn't seem to demonstrate that people are physically made out of control systems. My desktop computer isn't a control system, as such, but I can emulate a crude thermostat with a few lines of pseudocode...

while(1) {

while(DesiredTemp > ActualTemp) {runAirConditioner(); }

while(DesiredTemp < ActualTemp) {runFurnace(); }

}