You are thinking like a developer. Does the end-user care about what the art style is? If the game is USING the art style well the art style becomes invisible. It’s just a medium to communicate through. Things like the tech specs and the number of polygons and all that, that’s developer-minded crap that’s not relevant to the player or the game. They’re just features of the technology implementation, or perhaps selling points. But do you think in those terms when you play? no.
Camera angle + Theme is really most of how we define genre already.
Art style < Camera Angle
Theme is a big one though, many players tend to strongly prefer games with similar themes.
If you look through something like Steam’s recommendations list on a game, in general, almost all the recommendations will share camera style, and about half will be based on the same theme/mood, the other half will be similar in terms of game play.
Anyway to answer the question, genre indicate center of interest more than anything today. Ie what thing we will put forward as a key experience base on audience expectation in the game salad we are doing, Mass effect andromeda failed no because it was a bad game, apparently they prioritize the action elements that are better, but because it’s branded as a rpg and those elements where not prioritized, especially bioware rpg that are known for writing and cinematic dialog. And also because witcher 3 raised the bar of what a rpg could be.
If they had said MEA was an action game spinoff I’m sure it would be mildly better receive because the focus would be on the fighting system and rpg player would have stay away.
Similarly, when people say game like zelda have good story, it’s because they aren’t expected witcher and bioware style of storytelling, it’s relative only to the expectation of what story is in a zelda game (ie mostly the same role than porn (dixit carmack), emoting character to lead to the real action)
World of Warcraft and Warcraft 3 and DOTA are set in the same universe and use the same art style and deal with many of the same themes. Despite that playing and enjoying one of the games isn’t a strong predictor of enjoyment of the other two.
The point of genres is to make broad sweeping generalisations about game types, their various tropes, and the people who play them. With a couple of exceptions, you can’t make a useful generalisation based purely on art style.
The three games I mentioned have not only the same art style, but literally the same art. Yet there is no common gameplay, no common tropes, and no typical ‘Warcraft art player’.
On the other hand I can put up games like Warcraft, Starcraft, Command and Conqueor, Age of Empires and AI Wars, I can make instant generalisations. These games have little in common in terms of setting or theme or art style. Yet they basically play the same way, share the same basic tropes, and have the same set of players.
Take “RPG” for example. It stands for “role playing game”, but these days it’s more commonly used to describe “anything with stats the player can increase” whether or not there’s any role playing involved.
The thing is that a “genre” is just a label for a commonly recognised set of conventions. The label may be a misnomer, but the set of conventions it is applied to is still valid and useful as a descriptor.
That’s like categorising musical instruments based on their colour rather than how they make sound.