What you are saying relates very much to Descartes “Cartesian Other.” It is the shadowside to “I think, therefore I am.” We can never truly know if what we perceive is “real.” For example, you could be reading this and wake up the next morning from the long dream, which was your life.
Connected to that, imagine seeing a room. When you close your eyes, is the room still there? If so, prove it. The sounds or smells of the room do not prove that the room is still physically there. And if we were to stop perceiving, how would we know that the outside world still exists (if it does).
Likewise, are the other people around you true players, or are they NPC’s which have been programmed to act as true players? Liked your article, good read.