Classic Simon Says... game

Simon says is a children's game, where on player takes the role of "Simon" and issues instructions to the other players, which should be followed only when prefaced with the phrase "Simon says". Players are eliminated from the game by either following instructions that are not immediately preceded by the phrase, or by failing to follow an instruction which does include the phrase "Simon says". It is the ability to distinguish between genuine and fake commands, rather than physical ability, that usually matters in the game.

From Simon says on Wikipedia