EndersGame is the first of a series of five books, EndersGame being the most popular. The others are Speaker for the Dead, Xenocide, Children of the Mind and Enders Shadow.
His writing is inspired by biblical themes. I think it's because he's a Mormon priest.
He seems to write two separate sets of books - some really good (cited above, plus the AlvinMakerSeries?) with strong moral themes, written with a conscious intent to produce literary quality material. He also produces much less substantial work, possibly as a supplement to support the production of the other.