Who said art had to have a "story"?
Where is the story here? Doom has more of a story, and I'm not just talking about the opening text crawl.
When most game critics say "story" seem to mean plot, usually in the narrow terms as you'd find in a book, play or novel. But that's just hegemonic prejudice getting in the way, the same reason Ebert foolishly said games could not be art, because he is a FILM CRITIC and he only knows the way that films can be art.
Narrative can be so broad and subtle, any game that has progression has a narrative, you are exploring and discovering new things about a strange and exciting new world in such a visceral and personal way.
Take Left 4 Dead, a multiplayer zombie shooter, it actually has a deep and dynamic narrative that you may not be the creator of, but you are the auteur. The wild card is your own free will, the gambit is that your will can be manipulated and that has far greater artistic potential than a rigidly controlled.
I think a good analogy of games as art is to Architecture or sculpture. You can enter a building from any angle, you can take any values you like with you to use the building in any way. See a really well designed building takes account of your own free will.
That's the problem with plays, films and book they talk a lot about ideals of free will but very few actually grant that to their audience, they have to passively consume it as per the orders of the auteur. Read the book chapter by chapter, watch the film in order, some very good films know the benefit of ambiguity, this can be so powerful to an audience as it gives them a chance to exercise their free will and make a DECISION on what happened, who was right,who was wrong and not simply be TOLD what is.