Is it the win lose mechanic? The figuring out how to access certain paths. Being forced to stick with your choices? Or something else?
Something Else: The Immersive Experience of being able to see how your choices are shaping your path as the story goes on.
I like figuring out how to access certain paths. I don't give much of a tosh about winning or losing or sticking to my choices, i just like to see how a choice at one point may interfer with later chapters.
THIS. Although the stories from The Gamer, where it is more a set of alternate realities going down their own (single) path, are still great because the RPG aspect still gives you that sense of reward as the John levels up, even if it isn’t a result of the reader’s choices.