Amidst the choices given, I had to put "A technological achievement" as it's only in the past decade or so, when gaming has reached a level of graphical prowess to truly pass off claiming to be "realistic," that the topic of "Are games art" came about.
Now, I'm not saying that games like the original Final Fantasies, Donkey Kongs, Sonics, or Marios couldn't be considered "art" by some. However, at that time, these games were only conceived to be fun and entertaining, not to tell some grand story or tug at our heart strings. Nowadays, now that graphics and, to a certain extent, disc space no longer limit what can be created or what stories can be told, we can finally start trying to create games that are not only fun and entertaining, but thought-provoking and deep as well.
Of course, just like every other media, this does not mean that ALL games should be art, nor does it mean that every company that creates games is going to suddenly bend over backwards to make sure games have some unnecessarily contrived plot. What it means is we have the opportunity to create art, an opportunity that we are very likely squandering at present, but an opportunity that we may find can be used to much greater effect than any medium preceding it.