Joey Harker is adept at getting lost, he simply cannot find his way from A to B. On a school assignment he slips into another world and is rescued by another version of himself. Brought to the Interworld, he discovers the war between the forces of Magic and Science. Both sides need the Walkers to power the invasion fleets and Joey must grow up quickly.
As you would expect, there are a load of references to books and popular culture which can make for an entertaining game. Like reading China Mieville, it can be fun finding these but the story works equally well on its own.
It started as a television script but lack of interest shelved it and it was rewritten as a novel by both Reaves and Gaiman. It has recently been shown to some people as a novel on the off chance and Harper Collins have published it.
It does, I think, have an unevenness that collaborations do but the underlying idea is important: the artificial battle between science and magic. As both show, they have places in the world and both are necessary to make the universe up. Children need wonder and exploration in their lives to grow up fully. Though it seems done now in the post-Pullman world, bare in mind that this was conceived of in 1995 when the His Dark Materials trilogy had not been fully written. Both argue that rule by one or other power is a dangerous thing. The proof of this is in the equation: the alpha and the omega.
I do wonder if you read these children’s books in order that you would be watching the growing up and leaving home of Gaiman’s own children. I can definitely recommend this book as interesting.