[Vampyr]

All of them. The interface should be intuitive and easy to learn to the point where you don't really have to think about how you're going to manage or manipulate something in the game.

The visuals and graphics don't need to be realistic, but they need to be pretty and artistic. The music doesn't need to be groundbreaking, but it should set the mood.

And of course the gameplay has to be good, otherwise it doesn't even matter how immersive the rest of the game is, if the gameplay is bad no one will play it.