That game you play with your arms sticking out from around someone else’s body, and you act as their arms but cannot see.  It is not necessary to mount the leap motion or other sensor (gesture/hand detection) on the front of a screen or HMD.

This way, you could blindly control/move your hands and someone else sees the results and that someone could tell you how to move in order to accomplish what they want (tasks in the view they see). Or it could be a networked 2 player game where you have control of their in-game hands and maybe you can see each other but that means actions are mirrored, making it challenging to control.