I also didn't think much of Ico although I played it for only like half an hour to be fair. And I don't buy that 'its an old game, give it a break' argument - I play lots of old games, in fact I mostly play old, and they are all great timeless games. Neither I buy the 'you don't get it, its art' argument - art my a, even if it's an artsy game it still needs good gameplay and everything else. And don't get me started on SotC - Shadow of the Clunky as I call it.
Deus Ex (2000) - a game that pushes the boundaries of what the video game medium is capable of to a degree unmatched to this very day.