Immersive, Does its Genre a great service, Puzzling and very intriguing
Granted this was before PS3 or xbox 360, this game still stands out to me as an excellent Action Adventure strategy game. The game immediately becomes immersive and you'll find yourself playing for hours, not realizing you've past a great deal of time. The game is not straight forward. You are thrown into a mystery and have to figure your way out. I don't recall any dialogue in the game which added to it's mystique and intrigue. The sparse musical effects are also a great attribute to the game. There's plenty SFX and elemental sounds, but there's no sort of theatrical score or anything over the top here. You are completely immersed in ICO's mysterious, eerie, curious and vast world. The scenery still stands out to me as expansive and well done graphically for it's date.
If you still have a PS2 or interest in playing its classics, grab ICO and venture through his isolated environment and feel the level of anticipation rise as you wander around corners, never certain of lurking, fatal traps and foes or a seemingly impassable element and begin to deconstruct your surroundings and divine your way through.
I am still looking for games as enjoyable and immersive as ICO for today's consoles. If you enjoy ICO also see Fatal Frame II: Crimson Butterfly also for PS2