First lines: InterWorld

The Multiverse contains an infinity of universes parallel to ours. That slice of the Multiverse that contains all Earths is called the Altiverse, and the powers of Magic and Science are in a struggle to gain total control of it. Now, imagine you’re an average teenage boy with a terrible sense of direction, and then imagine yourself accidentally walking into that whole mess. InterWorld tells the story of what happens next.

Neil Gaiman and Michael Reaves — InterWorld
Once I got lost in my own house.