The greatest video game ever created?

[El Fangel]

What in your opinion is the greatest video game ever made? It doesn't have to be your favorite or anything, as my favorite isn't the best in my opinion.

I'm talking about overall. Story, gameplay, setting, fun, etc. The whole shabang.

Now, I have two requests. One, is I want to know why you think that game is that good. Sure, you can just post the name and leave the thread, that's fine. I'd like some elaboration though and will rep anyone that does.

Secondly, It doesn't matter if the game is years old, if discussing significant plot or ending material please put spoiler tags. I probably will add most of your games to ones I plan on purchasing if you think they are that good and would rather it not get spoiled.

So, what is in your opinion the greatest game ever made?