I think visual novel games are actually quite different to read then a normal novel, although this of course depends on the visual novel in question.
But for example, Tsukihime and Kara no Kyoukai, both written by the same person and about the same setting, one a novel, one a visual novel game. The way the story is told is about the same, but the way you are reading it is quite different, at least it appeared to me that way. I think for teenagers the visual part encourages them more, and the way text appears makes it easier to continue reading. So if the story is good and they have less problem reading it, it might just become more popular then reading (like how anime is often popular with people who hate to read).
The effect visual novel games have on my life? I actually was thinking about with which girl I should end at one point XD (IRL that is
]). But usually a good novel would prabably have the same effect for a dreamer like me, I keep mixing reality with stories
] But the effect of choosing is a new aspect in the visual novel games, hope I don't get too cought up on that one XD