GCompris - Educational Game for Children 2 to 10 years old.
HoDoKu - HoDoKu is a sudoku helper written in Java and available in English and German.
Tux Paint - Tux Paint is a free, award-winning drawing program for children ages 3 to 12 (for example, preschool and K-6).
Simple Sudoku - Freeware Sudoku Puzzle Maker and Solver
GENIUS MAKER - The Genius Maker is a Mathematics and science education software from Golden K star.
nsudoku - A Sudoku game made with ncurses.