Guessed by Keybladewielder
Perhaps moreso than any other game, this is the one that most deserves the title of a "masterpiece" - because it is truly and genuinely a work of art. It never set out to revolutionize gaming or to provide the next biggest adventure with loads of things to do and places to explore, or to be a challenging game you need to master or any of that. No, Shadow of the Colossus is pure art - it's a breathtaking story being told in the best way it can be, and in this case the best way to convey it was through a videogame.
As much as everyone went into this because of the appeal of just killing some giant monsters (never mind teenage me), the game is quick to make you question your values and realize this "cool" thing maybe isn't all that great. Yet, you keep on going, because just as Wander himself, you become attached to this idea that it's all for a good purpose, blinded by this idea that you must be on the good side of the story even if everything points the other way.
It's the way this game screws up your morals that makes it truly shine. By making you doubt your intentions and your actions, yet still providing an end goal so clear and obvious that you can't help but keep going in belief that this is still a videogame and you, the hero, will be awarded a happy ending. That's why the story of Shadow of the Colossus is best conveyed in this format - breaking the rules of what you expect from a videogame is what makes it such an unforgettable journey.
*partially quoted from last year*