It's a sort of you know it when you see it (play it) thing. Something along the lines of becoming more than the sum of their parts and also using the interactivity that the medium provides.

When I played TLOU I enjoyed it but I kept thinking "this might as well be a TV show and lose nothing for it". It's a well made story, presented with technical prowess in an interesting setting, then it's also a sort of well made stealth cover shooter but it just doesn't come together. That's not to denigrate the individual efforts and art made there, I'm not saying it's shit, but there's just so much potential left on the table there. If you can 1:1 translate your game into a TV Show, like TLOU, why was it ever a video game to begin with, if you come at it from an art standpoint.

I don't know if you played Gothic or S.T.A.L.K.E.R., those are quite similar in how it's a great setting, well made (well, bar eurojank), the story is serviceable at best and for stalker especially veers off into nonsense at the end but crucially neither games would work as a book, or a film, or a visual novel. You could use the setting, sure, the art design and lore and stuff is solid enough to carry lots of interesting stories and have been used as such but it'd lose such a tremendous amount of what makes it great that it just doesn't work. The first episode of Gothic (TV Show) is a man who walks into a city after pullign some beets and buying his way in. Or possibly sneaking in. Or maybe he murders someone and steals the uniform. Sure, that can be well made, but the point of Gothic is that you have all these options, go nuts. Fuck, transform into a raptor and cause mayhem then revert to human in the confusion, game will let you, but that's the sort of thing that can't be translated to other mediums well.

I'm currently playing through Diaries of a Spaceport Janitor, that certainly goes more the indie artsy route, and I love it because again, doesn't work in another medium. What makes it great is that it hits the line between the trash collection being tedious and frustrating, but still engaging enough, that it conveys the feeling the little sanidrone would have through interactivity. It sucks, but it is your only hope. And then the rest of it is also just very well made.