Dr. Kawashima’s Brain Training: How Old Is Your Brain? also features a sudoku mode, for when you want a break from training.

Sudoku is the hugely popular puzzle game that involves filling in numbers on a grid so that the numbers are not repeated across lines, columns or in smaller sub-grids.

Normally played with a pen and paper, sudoku is played on Nintendo DS using the stylus. Numbers can be written on the touch screen and you can also make notes along the edge of the grid, like in the paper-based puzzle.