Videogames are an artform. For me, that is an indisputable statement. It is not a half-statement or a statement full of those nasty little "exceptions". All videogames are art. Every single one of them. Yes, even that cutesy but extremely stupid and riddled with bugs "My Little Petz Shop" DS game your little sister has. Some, however, are better art than the rest. Here's why:
First, let's take a look at what videogames have that is unique over all other kinds of arts. That is, of course, interaction. Now, while videogames themselves integrated most others forms of art (think; how many videogames feature paintings made by the videogame artists themselves?; or have amazing sculptures in their environment? (think Bioshock) and we all know just how similar cutscenes can be to movies...), that in itself does not a new artform make. Making a painting out of macarroni does not suddenly turn it into a "new artform". It is the fact that we can interact with videogames that makes them so incredibly fresh.
Now, you could question wether something like Dear Esther is even a videogame then, considering how little interaction it provides. But it does provide a lot of interaction, if you think about it. It's just that it is more of a contemplative kind of interaction. You wouldn't say a movie doesn't tell a story because it is slow, or because it doesn't have a conclusive end. You would think of it as a different kind of movie. And that's a key word: different.
As such, every kind of videogame can be art, it's just that it is art fine tuned to a very specific kind of people, sometimes bigger or smaller in number. La Mona Lisa wouldn't be considered such an incredible piece of art if the elite art-lovers were all into football instead of painting. In the same way, "art games" are considered such because the elite of videogame-lovers, the people who are the most knowledgeable about them, think they are good pieces of art. If it turned that all of us "hardcore gamers" adored FIFA, FIFA would be considered an art.
So then, let's not go saying anymore that a game isn't art because it belongs to a specific category of gaming. Let's, instead, start saying that said category of gaming is BAD art, or a specific game is STUPID art. But art nonetheless.
Having taken that out of the way, I would like to consider what makes a videogame a GOOD example of art. Take the aforementioned FIFA. Most of you probably consider it the antithesis of the artistic videogame. Yey for me, it is a perfectly good example of videogames as an art. As much as "art games" exceed at making you feel like a desperate man on an island, or a filthy little shit because that old woman is dying in a cemetery, FIFA exceeds at making the player feel like an over-arching entity controling the footballers. It is, you see, a videogame created with finesse.
Finesse in that it knows perfectly well what it needs to become a great example of a football sim. Year by year, it's developers perfect every aspect of the game, everything gets updated as much as it needs to be. And people love it. 9 million people buy this game every year. It is critically acclaimed. And yet only because it resembles a sport instead of a philosophical journey through the mind and body it isn't artfully made?
I would consider, for instance, that taken solely by their quality as videogames, Alpha Protocol is a worse videogame than FIFA. Yes, Alpha has an interesting story and premise, but when you have on the one hand a game that does every little thing that it sets out to do so close to perfection, as opposed to one that fails miserably in two thirds of its intent, you have a clear winner.
That does not mean, however that bugs equal an inferior game. Fallout New Vegas is, in my opinion and that of many other fans, better than Fallout 3 despite being a way more broken experience. Both being so similar (same series and engine), the art and story of New Vegas definitely overcomes it's general bugginess. Is it a better game than FIFA? Objectively, it is. For me, it isn't. But that is solely because I am a story guy more than a sports guy.
All these comparisons are, however, basically useless. Because every single player will love different games and be attracted to different genres. Game development is a multi-faceted enterprise, with thousands of different variables and dozens of different kind of artists needed. It is in the combination of all this areas of game design that a game is defined as art. Some games will have better UIs, others dreadful stories, some may be gorgeous but a drag to actually play and some may have incredible gameplay but lack a story of any sorts.
Let's not judge a game's artistic merits simply because it doesn't have a story or it didn't make you cry. Let's start judging games simply because of how good they actually are at what they are trying to do. Do not say that Modern Warfare 3 is a bad game simply because you dislike it's community or business model. Think of Modern Warfare 3 as the game that bests provides addictive unlocking in a multiplayer FPS with explosions and bros. As that is what it is trying to be, what it should be, and even what it is marketing itself to be. CoD is a fine example of art. It just may be that it's not a great example for YOU.