The software makes the text a just - right level of challenge for readers, with immediate feedback (as on the Curriculet articles and TenMarks) on student responses to questions. (citybridge.org)
The Wii version was created with the notion that players would settle in and play through long stretches of the game, which resulted in just the right level of challenge and playability. (nintendoenthusiast.com)
I played it with Y10, 12 and 13 and they were all able to complete the game with the right level of challenge. (tes.com)