I may be bias with this one, but this is my favorite game of all time. The people who made this game knew what they were working with, how much space they had, and most importantly how to make a good game.
This game executed its premise perfectly, the world and puzzles are embedded to the point where you couldn't not see it working without each other, and the art and sound of the game makes it almost timeless.
Of course it's not perfect, what game is? But the fact that this game exists at all is a miracle unto itself. I'm not going to even promote preservation, I'm being selfish right now, I want this game to be here.