It's a Zendrum. www.zendrum.com
anyone who's read the book can tell you that there isn't a bit of the fantastic anywhere in it.
Spoiler (click to reveal)
While Terabithia is technically just an imaginary construct of the kids, it definitely is full of magical and fantasy elements. Like Giants.
They are simply realizing that on screen.
However, this marketing will be a massive blow to anyone expecting a nice little fantasy film.