Making a game is similar to making a movie in many respects, chief among which is the decision whether the small army of people required to make the project happen are doing so for monetary or artistic reasons
Ideally, it would be both, but for console games there is a third motivator which would put Horizon Zero Dawn into a neatly labelled basket alongside The Last of Us, Uncharted 4, and a few others. Hollywood is no stranger to similar things - Oscar bait might not be a movie genre in its own right, but it is still regarded as a loose abstract category that a lot of movies easily slip into.
A similar concept is slowly forming for console games and especially with Sony for the PlayStation. Simply calling such games killer apps wouldn't do them justice, mainly because their artistic aspects put them beyond mere utility as is usually the case with the idea of a killer app.
Horizon Zero Dawn is now doing for the PlayStation 4 Pro what Uncharted 4 did for the boring old regular PlayStation 4 and The Last of Us did for the PlayStation 3.
All three games are aimed at the broadest audience possible, in accordance with current trends in theme, tone and proven mechanics. They are crafted with the intent of treating complex, intimately human issues with a degree of maturity, while being as unoffensive as possible. A great deal of stress is put on the story and characters. In terms of presentation, they are very cinematic and have clean visuals with just enough grime and clutter to allude to realism. All these similarities come from a long list titled "Sony GOTY candidate", but there is more to it. Each of the three games used as examples above was advertised as a huge selling point for the corresponding PlayStation hardware; they were widely praised by fans and critics, and while silent cries of 'no soul' could be heard here and there, they were easily drowned out by a constant background beat of critical consensus punctuated by fan-boy hype.
I don't think I've run across a term for this kind of game before. It is Oscar bait, killer app and some sort of selling point or vindication for the existence of a particular generation of PlayStation consoles in a technological and artistic sense - all at the same time.
I just can't shake a feeling that there is some other sort of motivation behind the production of these games, other than the two traditional ones we already know from movies. Partly they are meant to sell copies and maybe even more importantly - sell consoles. From another angle they seem to be Sony's way of playing patron to Truly Artistic Endeavours in Game Design(tm) while at the same time praising technical aspects far more than any artistic merits, probably because art won't sell your game or console, but a high frame rate, pixel count and detailed facial animations will.
Sony's whip seems to have cracked open the box containing all the highest polish lowest common denominator elements of game design, PR, marketing and distribution, while maintaining an air of sophistication. The odour of a perfectly deconstructed and then reassembled product hangs heavily over these and similar games. You name it and Sony's GOTY candidate/console seller has it all. The critics are powerless since they have very little they can aim their canons at with even less argument-shaped ammo to go around.
While I don't necessarily disapprove of such titles for the future. They are certainly significantly better than another Call of Battlefield every year until the end of time. I can't help but feel that as far as reasons for making a game go, whatever is going on behind the scenes at Sony - somehow feels dishonest and duplicitous.