What is art? To me, art is everything that makes me discover something new. Video games are about fun, and fun is basically discovery. It’s the discovery of some skill we have, the discovery of how a certain story will end. It’s the discovery of a new technology, or maybe the discovery of a new type of appearance or visual style.
It’s clear that video games are pure art under this optic. This includes even games made purely for cash, like gambling games or aggressive free-to-play games. We discover something about ourselves in any case. Of course, that “something” can be bad as well.