ICO: Castle in the Mist

A boy with horns, marked for death. A girl who sleeps in a cage of iron. The Castle of the Mist calls for its sacrifice: a horned child, born once a generation. When, on a single night in his thirteenth year, Ico's horns grow long and curved, he knows his time has come. But why does the Castle of the Mist demand this offering, and can the castle keep Ico's destiny from intertwining with that of the girl imprisoned within its walls?