With a few glowing pixels, an electronic display, and a joystick, a "d-pad," or even just the touch screen of your smartphone, you can immerse yourself in other worlds and make all the right moves to level up or blunder into a death trap where it's instantly "Game Over." How did we get from primitive yet compelling games like Pong to the reality-hijacking Pokemon Go app, which sent people all over the globe stumbling around their neighborhoods in...