The word Art is not tightly defined. As such, anything can be art and everything is art. That's not particularly helpful so the alternative is to say that enough people claim it is art then it is.
Thus games, RPGs, everything is and can be art.
Is it high art? Some people believe that high art is anything that draws a strong emotion or awe. You can have a piece of art that doesn't become art until someone experiences it (many art installations in national galleries follow that principle). It's similar for RPGs. However, I believe (for what it's worth) that the art installation without anyone interacting with it is still art.
If an RPG can offer you an emotional experience that sticks with you then it is high art. No-one will believe you cried during your Vietnam game but if you did then it was a moment of Art.
Looking at the art-form vs artwork, RPGs represent an interesting iterative paradigm. Creating a good game is an art-form - as one must labor to bring many separate elements into a package. There is a balance of technical issues (making writing clear and mechanics well explained), aesthetics (artwork without distracting, displaying the setting without missing elements), and the work of finding the right elements for emulation or simulation. Thus the product of the writing is a work of art. In turn, its used as a inspiration/tool for the art-form of running a game session which produces the performance artwork of a well played session.
So I would definitely stand by the idea that games are art as a rule, rather than an exception. Gross mismanagement can drop them out of the category, but that is true of everything - as as follows - up for contemplation.
Now if its enjoyable art, worthwhile art, or "agitprop" is of course up to the interpretation of the final consumers. I can't really think of any practical way to get around the argument "I know it when I see it" (hey - its good enough for a US supreme court standing on censorship). Indeed, I greatly embody the sentiment because I like the forms produced by Lockheed and Sukhoi than those produced by Michelangelo and Jackson Pollack. The had a high accident rate, handling problems, and a short service life - but it certainly has that rocket-man spirit of the 50s and looks like its going fast even when standing still. It is sublime, if not necessarily good.
I suppose I could continue my habit of name dropping and mention Marshal McLuhan of "The Medium is the message" fame. That is a large part of what makes these games what they are. There is a lot more flexibility than a computer game, more interaction than a novel, and more drama than a movie since not all elements are pre-planed.
Its a lot like forms of textbooks and re-enactment. A text about the civil war could just be a list of major battles, who commanded the armies, and which side was victorious on a given date. Adding reproduced Daguerreotypes, personal accounts, and sidebars about equipment used improves the form to be more engaging, and thus easier to learn from/interact with. Watching someone actually load a black-powder firearm and understanding the steps that go into firing it gives an even better view of what the people on those old battlefields experienced. Of course, this understanding probably doesn't help on a standardized test - but its certainly a more visceral form of understanding - that is art.
Continuing with this concept, we also have that games tell stories through play. (This is perhaps the biggest impediment to Mr. Ebert seeing them as art - they are interpreted in a very different manner.) A novel (and most movies) is supposed to be storytelling over time - showing how events build up to the conclusion and how each element fits in. Games are in the now! Should you go for the objective this second before more opponents show up, or find health to be better prepared when they do? Can you use rockets now to save health, or wait until a bigger threat comes up? Whether you can barely survive one rifle bullet or shrug off fifty dictates how the game is played and the tension faced.
The story you experience, not the story you're told or analyze later. Ultimately, art is much about what you feel rather than the cold analytical judgment. A battleship looks powerful, you can see why they we're symbols of national strength - yet in the scheme of things, they were white elephants. The spires and buttresses of a Gothic cathedral are supposed to make people feel small, just as they' would be tiny next to god - enclosing a space is rather secondary.
@SheikhJahbooty Can we start a new thread discussing your game session? I've gotten more e-mails about my half page "Sputnik Lost" than D&B somehow. (In fact, I just got someone's proposed revision of SL last night!) I really want to know how it went, and think using Zardoz embodies the themes of the zone perfectly. And how did you describe NEST 2?
Games of imagination are never truly done. Yet tomorrow we shall start another one.
Good lord, no! Authority on semantics is only derived by usage from the masses! It is broad opinion that counts, not the opinions of a few. Therefore, all opinions are valid and hold equal sway. Becoming an expert only makes you a novice in other areas. You can't be an expert in all.
Does art have to effect you emotionally, permanently? Some traditional art, masterpieces even, don't effect me emotionally at all. If I look at a portrait by titian, all I see is a face.
Art is expression. However you wish to express yourself is artistic. However the moment you label something "art", you've devalued it's purpose.