For me personally, art is about expression projected onto a medium for others to explore. This medium could be anything from music, video, writings, drawings, sculptures, and yes video games too.
There's however a borderline for me when something becomes more about it's practicality than its expression.
- The difference between and editorial, and a poem.
- Architectures as just being another building, while others might catch your eye.
- A blank canvas, and an abstract painting.
- A toy, and an interactive sculpture https://www.youtube.com/watch?v=BZysu9QcceM
If you apply the same thing to games, you'll find similarities where you might draw your own line if it's art or not.
Is Tetris art?... Well MoMA took it into their art collection... does that mean it's definitively art for me?
Well, no, because I don't really get anything more out of playing Tetris than just enjoying it as a puzzle game.
You can make this comparison to abstract art. I don't understand abstract art but there is something pleasing to the eye with some of them.
So, point being, whether if you experience the creator's intended expression behind it or not, games itself is a medium for art.
https://www.youtube.com/watch?v=dINgx0y4GqM
https://www.youtube.com/watch?v=IAs4Dy-lh8E
https://www.youtube.com/watch?v=LSm-UzWzO2E