This system would require direct connection to signals from your brain, intercepting and consuming them, never reaching your muscles. Resting comfortably with REM-like paralysis, you control your game character naturally and intuitively, moving it and not yourself, all from the comfort of your couch.
Technology like this already exists in its infancy, such as providing moveable arms and hands to those who have lost them:
"Move Arm" ---> Engage Robotics ---> "See Arm Move"
"Move Arm" ---> Animate Game ---> "Feel Arm Move"
The current feedback loop in robotics is limited; we can't make Luke Skywalker's robotic hand flinch with needles yet. For things to work well in a video game, you'll need to feel your actions, just as a runner feels their foot-strike flick off the ground.When will this technology be available? What bottlenecks need to be overcome for it to exist? How much will it cost? What other applications could it have? Will it be released before Episode 3? ;)