Nintendo worked with Dr. Kawashima to develop a game that could be used to maintain mental fitness. The result was Brain Training (Brain Age in NA). It is a puzzle 'game' that tests the user with certain activities, such as stroop tests and mathematical questions. It also contains over 100 Sudoku puzzles (Outside of Japan).

The game contains a variety of games to test your brain, such as Calculations x20, where you solve 20 math problems as quickly as possible, and Head Count, where you must keep track of the number of people inside of a house while people enter and exit it.You unlock more games by performing daily trainings. It encourages users to play daily, thus, keeping your mind sharp.   

Users can also take a Brain Age Test, which will calculate a Brain Age for the user based on 3 different tests. These tests range from memorization to observation, and focus heavily on time spent completing the activity. 

With daily training, and quite a number of Sudoku puzzles, players will find tons to do with the Brain Training game.