You might want to take a look at the "young adult fiction" Gone series by Michael Grant.
Instead of being pulled into a "fantasy" world, the child inhabitants of the town of Perdido suddenly become isolated from the rest of the world by a seemingly impervious bubble. Anyone over the age of 15 years mysteriously disappears leaving no adult supervision and the child population to fend for itself.
Some very subtle changes start to happen within this isolated shell, some of the children discover they have new found powers such as being able to move objects through telekinesis, or shoot bolts of energy from their hands. Nature in the world itself begins to alter, lizards grow wings and can fly, the local hyena population submit to the control of an evil force residing down a local gold mine, cats can "warp" themselves from one location to another.
I'm not a huge reader of this type of fiction, but bought the books to get our oldest lad (12) more interested in reading. He couldn't put them down so I decided to have a read as well and the first two that I've read (Gone and Hunger) are quite enjoyable.
Not that this should be at all important, don't be put off by the covers used in the first publication runs. The latest paperbacks and hardbacks have way better artwork where you wouldn't feel self-concious about pulling the book out of your bag to read in a public place.