Is the leader of the seder supposed to hide the afikoman so that the kids can find it, or are the kids supposed to hide it so that the leader can find it? And what is the point of this hide-and-seek game anyway?
Common practice (at least from what I've seen in the Ashkenazic world) is the father hides it. Rambam says the kids have to steal it and hide it. Either way, it's to grab the kids' interest and keep them awake.