In the Sudoku game (more precisely, the "Latin square" game) you need to drag the correct objects into empty cells of a table. You win the game when all the squares are filled and in each row as well as in each column every object appears exactly once. Sudoku is a logic game which is suitable for kids 4 years old and up.
The easier levels will be best for preschoolers 4, 5 and 6 years old. The medium levels for 7, 8, and 9 year olds (elementary school). The harder levels for 10, 11 and 12 years olds as well as adults. Sudoku is an educational game to train spatial reasoning, IQ, attention, logic, basic math and geometry skills.