Ico is one of those rare games that can use the minimum of dialogue and gameplay to maximum effect. You grab a ghostly girl by the hand and try to escape the castle with each other. But Yorda isn't as agile as you so you have to find a way round for her. This sets up a lot of clever puzzles to solve and they're all satisfying. The combat's as basic as pressing Square until the dark shadows go away but at least it works, though it does get annoying when you get knocked out while they fly away, causing you to hammer at the X button hoping you'll get up quicker and rescue Yorda.
It's a simple game but a beautiful one. Every part of the game is expertly designed, if a little washed out. If any game were to be considered art, this would be it.
Despite its simplicity, lack of cutscenes and very short (can be finished in 7 hours tops) it's a beautiful game about two people helping each other out, just for human kindness. It's one that can grab your emotions in ways other games can't. You need to play this game at least once.