Bring everyone to gallery view and introduce the actions: touch your nose, touch your head, move, freeze.

Play a couple of rounds, inviting the group to do as you say. 

If people get it wrong, for example move when the should be frozen, tell them they’re out and they should turn off their camera.

Introduce a new rule: make everything opposite! So when you say move, they have to freeze and vice-versa. Same with touching: head means nose, nose means head.

Keep playing, by calling out actions, knocking people out if they make a mistake. Last person with their camera still on wins.