Want to resolve the “games as art” debate in 15 minutes? Play Passage.
It’s difficult to define art, but Passage refutes every objection I’ve heard to the status of games as art. While I’ve never doubted the potential of games in this respect– and I believe them to actually be superior for art, at least in terms of sheer power– Passage is the clearest and most concise argument I’ve ever seen. Passage uses the unique properties of the medium to convey its insights in a manner that could not be done in another medium.
You can read the artist’s statement (linked from the Passage download page), but as with most creative works, I found that the artist’s explanation of the work to be unsatisfying and limiting. Read the statement if you must, but play the game first. Games take only five minutes, and you may want to play a few times.