Like the game. A camera on top of your screen senses your motions.
You point at the screen, the cursor moves.
Move hand down, you scroll down (&vice versa)
You nod, it means enter. Etc.
The user can assign certain movements of his or her choice to various actions.
Pro: No more mouse-arms.
No more sitting hunched in front of your screen for hours on end getting a pain in the neck. Stay in shape.
Con: Not to be used for adult surfing.