I mean, how about this: The Nervegear acts as a second body to the brain and a second brain to the body. The former is for the input/output system, and the latter is to put the body into a sleeping state. Why don't we scan for what kind of signal is being sent to & from the brain, and then store the data for use in-game? Like with sight, the eyes detect light and convert it into electro-chemical impulses in neurons. why don't we scan that and then write the information we want to give to the player based on the information we get? Of course there will be a lot of calibrations for each person, but I think people are willing to do that to go to the "game world". Also this maybe useful for medical purposes.