A young boy in a magical world has been born with a strange deformity: large horns that jut out of both sides of his head. The people of his village, fearful of retribution from above, feel they have no choice but to sacrifice this mutant child to appease their gods. To that end, they have taken this boy, named Ico, to a massive, supposedly deserted castle and left him in a giant urn. But when the urn breaks, spilling Ico into the bowels of the fortress, he will soon find his adventure is just beginning. Along the way he'll meet a mysterious princess who has been held captive in the castle for untold years. Although they cannot communicate through speech, they soon forge an unspoken bond, and it is clear that if either of them wants to make it out of the castle alive, their destinies must remain intertwined.
Ico and the princess do not speak the same language, but this isn't to say they don't interact. Quite the contrary, as their relationship is a key element to the game. Ico's main goal is escape, but he cannot and will not leave the princess behind. Although she has limited power in terms of mobility, she has the ability to open certain doors blocked by massive idols. Ico has to do the majority of the grunt work, however, grabbing the princess' hand to pull her along to new locations. He can call her when she's far away, and help her up steep ledges and across long jumps that she could not normally make on her own.
Don't assume that this journey will be a pleasant little jog through the castle, because plenty of obstacles stand in the way. The castle isn't a plain arrangement of straight hallways and open doors. Rather, players will have to use brainpower to solve the puzzling twists and turns that the fortress has to offer. They must run, jump, climb, swing, and explode objects and traps in their path, all the while finding an easier way to bring the princess through it all. And lest anyone believe that the castle is actually abandoned, the duo will be continually pursued by shadowy creatures intent on dragging the princess back to the prison. ~ Jon Thompson, All Game Guide