Since time immemorial — or at least since Pong — one barrier that has stood between gamers and total Tron-like immersion in their video games has been the controller: the joystick, trackball, mouse, light gun or whatever. This year Microsoft demonstrated a technology, code-named Project Natal, that enables players to control games using only body movements and voice commands, no controller required — the gamer's body becomes the controller. Project Natal uses several cameras, plus a highly specialized microphone and a lot of fancy software, to track the gamer's body and interpret his or her voice. You move your hand, and the Master Chief (or whoever) moves his hand. It's that simple. And that cool.