Invitation to the game
A secretive program, known only as "The Game,  is devised by a controlling government for an unknown purpose.  One day, a destitute youth, Lisse, and her friends are selected to take part in The Game.  Their world becomes one of fascinating adventure, but as the challenges increase each time they play, The Game begins to take over their lives...
Science fiction, Dystopia, Large type books, Children's fiction
Monica Hughes        
Monica Hughes OC (November 3, 1925 – March 7, 2003) was an English-Canadian author of books for children and young adults, especially science fiction. She also wrote adventure and historical novels set in Canada, and the text for some children's picture books. She may be known best for the Isis trilogy of young-adult science fiction novels (1980–1982).

**Source**: [Monica Hughes](https://en.wikipedia.org/wiki/Monica_Hughes) on Wikipedia.