The thing is, the best game of all time would have to be something that is infinitely replayable for me. While I did enjoy Ocarina of Time immensely, I don't think I would have replayed it more than three or four times before the repetition of tasks and environments tired me.
Now, put me in a deserted island with a game like Starcraft, Warcraft or Civilization, and I would be entertained for many, many years. Put me with any linear story-based game in a deserted island, and I will be feeling miserable after a few weeks, if not days.
Some people would put online games here, such as all the excellent FPS titles like Call of Duty, etc. I personally am not a fan of shooters, but I admit those games are pretty much almost infinitely replayable as well.
Anyway, that's my personal criterion for choosing what the BGOAT should be. I respect your right to disagree with me.
Make sure the shadow you chase is not the one you cast.