Show the goal, then the first input
Start with the win condition in one sentence: “stay alive by jumping,” “turn all the lights off,” “get the puck in that goal.” Then show the first input once, slowly. People remember what they can imitate. They do not remember a tour of every advanced tactic.
Let them take the second attempt. Commentary should wait until after a mistake, and it should describe the decision, not the person. “The gap was already closing” is useful. “You always jump late” is not.
Protect their right to a clumsy round
Grabbing the device to “just show them” often teaches helplessness. If you need to demonstrate, ask first and hand it back after one example. Celebrate a clean recovery or a good question. A first high score is optional; a first understanding is the actual lesson.
For children, agree on a stopping point before play. Lives and ads should be explained in ordinary language: the round ends, a short video may appear, clicking it is not required to keep a real score. Teaching the arcade includes teaching the exit.