A story can be engaging and linear at the same time, most VN games have mechanics that force the player to make choices, as in, they can do multiple things in a day, but they cant do everything in a day. a lot incorporate money in some way as another resource to keep track of. but if the VN you're making is too short it might not have enough time to make use of these. I'm no expert in the genra, but there needs to be gameplay somewhere to keep it from being left mouse button simulator