Complex sentence: The leader then moves around and all the children have to mimic the leader's actions players who mess up or do not do what the leader does are out of the game, and the last person standing other than the leader is now the new leader.
Split into simpler sentences: The leader then moves around and all the children have to mimic the leader's actions. Any players who mess up or do not do what the leader does are out of the game, and the last person standing other than the leader is now the new leader.