Like Brushing Your Teeth
When you start to play it you can choose the brain test, or the brain training.
When you do this you can test your brain on how old it is, do this from time to time to see how much your brain has improved or deproved, you get three exercises you need to complete before you see how old your brain is, 20 is the best, 80 is the worst.
The mic of the DS is also built in, you need to count to 120 as soon as possible (though you can already stop at 50) and say the color a word is written in, when the word says black but the color is yellow, you need to say yellow
Then there are the exercises where you don't need to speak, like counting the people going in and out the houses, calculating, remembering words and more, all to improve your brain
Then there also is this sudoku you can play as an extra game, there are enough puzzles to be busy for a while, though I never really was a sudoku fan, but for those that hate writing it down in the newspaper this is a very helpful game
Notice that when you first play this game you try to do it daily to get stamps to unlock new exercises and see how old your brain is, it's addictive indeed.
It's like brushing your teeth, sometimes in the weekend after I had my breakfast I go play Brain Age, and it helps me to wake up! My entire family plays it now and overall it's a good game to help you keeping you alert, but I don't think that the ages it says your brain is are correct sometimes.