There is a problem with the question "What makes a game art?", it presumes that the artistry of games is in question. The question that the entire gaming community from players, to students (this is where I fit in), to professional developers should be asking, and pressing others to ask is, "At what point does a game cease being art?"
I am going to illustrate my point using Red Dead Redemption...that being said many games came to mind that I could have used, Fallout 3, The Legend of Zelda, even Modern Warfare...but as I was putting this thought together in my head Read Dead kept on jumping out at me...
Let's for a moment, igonre the fact that Red Dead Redemption is a video game and look at a picture...
Imagine that the above image was created with oils...could it be considered art...emphatically yes, I believe. Now imagine that the image was created with pastels, still art? How about charcol, or graphite, is it still art now? I think you see my point...technique and the tools used do not matter as much as what is reading to the viewer/player...thematically this image shows a man watching his entire scope of life be washed away (and bandits robbing a train if you're really paying attention), whether created with oil paint or pixels on a screen.
To take this one step outside of the painting, you can imagine that just sitting on his horse, our center-piece would be rearranging his belt, or maybe stretching an over-used limb...does this movement bring us to the point where what we are looking at has ceased to be art?
Now that our center-piece is moving...coming to life...let's add a score to the scene...are the notes somber at the witnessing of the destruction of the American frontier, is there a hint of excitement at the prospect of dispatching some bandits, or joining with them? Has the music brought us to a point where this ceases to be art?
Now a step further, you have a controller in your hand...make no decisions yet (I know, there's action down the hill, bear with me)...just look around, everywhere is screaming at you to do something...some places are screaming at you to hurt others, some to rescue others, some places scream at you to relax, some to laugh...has this new level of exploration taken us out of the realm of art?
Now make a decision! Do you exterminate the bandits and save the day, or do you help the thieves in their dastardly deed?
Either way you're pulling out your gun...is it this that makes it not art? I would certainly think not!
Is it the fact that the game sets a goal? How is this different from leading lines in a painting or photograph...drawing the player/viewer's attention where you want...of course they can always take in a work of art as they please, while the artist has the ability to make that enjoyable or uncomfortable and tedious, either way can bring about it's own kind of success...
The point that I am trying to illustrate is that a stance denying the art of games, has to deny it from the bottom up, not the top down...
Some may be thinking, "Well yes, the world in Red Dead Redemption is incredible, and the score is moving, but that makes Red Dead a vehicle for displaying art, not art itself!" To this I would answer that the world and score were created uniquely as Red Dead, the game mechanics, and it's world, and music are not seperate entities...the mechanincs are the tools given to the player to take in what was created for them...
"Artists lie to tell the truth, while politicians lie to hide the truth" - Evey Hammond