Subroza.nl is a very successful Dutch internet thriller written by author Marcel van Driel. The book is about two kids who inherit a computer program left to them by their late father Colin DeVries. He has hidden this program on the Internet and the children have only three days to find it. Readers of the book can also go online to the Subroza website and play the same games (and more!) the characters play.
On this website you can find a preview in English of the games, puzzles and websites that Colin DeVries created for his kids.