The base idea of story telling is to keep the the audience with the interest to keep going, curiosity to keep reading or playing or watching something that gets them attached wether its through the character development or through the world a good story is something you remember. For example in the last of us (a story about zombies) gets you attached to the characters in the first few seconds showing that there a family makes you bond with them and when the inevitable happens it makes you feel for them thats a sign of good story telling. Also sometimes the main character never has to speak for there to be a great story like in half life or The legend of Zelda its the world that you connect with and the adventure you going on the people you meet . So the story is something that happens its something you put time into and it should show.
Visual style is something that has the go with the story and mechanics of the game. Its the way you go, the characters, the environment and so on. Wether you’re making a game focused on realism like Uncharted or or focused on on simplicity like Tomas is alone its the way you use the development of the design in the game.