Edit: A wonderful response to the article from Brian Ashcroft
Half-Life 2 stirs my emotions in a number of ways. Does that make it art?
A game itself may or may not be art, but the components, be they physical or electronic clearly are. It's not even a question. A masterfully crafted chess set isn't art? How about the backgrounds in a Final Fantasy game? How much art in a game does it take before the entire thing is an artistic experience? That's up to the artists and the person experiencing the game, and not anyone else.
I define art as something that stirs emotion in the person that experiences it. This allows things that were not originally meant to be art to be presented as such and still succeed. Andy Warhol agreed with me. It also means that some people aren't stirred and don't recognize the artistic value. That's fine, too. In my world, that's how it works.
Most really great art also has detractors who claim it isn't art. I kind of like the idea that appreciation is a zero sum prospect, where others' dismissal allows the rest of us to experience an even greater level of emotion towards the piece.