This is one of the most unique games I have ever seen. It helps you train your brain and get smarter, but somehow, it presents it in a fun way! Before I tell you all about it, I have this to say: BUY THIS "GAME"!
There are three options of play on the main menu: Quickplay, Daily Training, and Download. Quickplay let's anyone check their brain age, the games way of measuring how smart you are (the younger the better), without entering their personal info first.
In Daily Training, you need a data file with all your personal info put in. You can check your brain age or just train your brain and try to get the best results you can. The game stores graphs of everyone's progress and you can view it by selecting "Graph" in the Daily Training menu. You'll want to keep playing on a day to day basis because the more days you play, the more activities you'll unlock.
This game actually doesn't support multi-card play, just download play. You can either send a demo to a friend, or go head to head with up to eight people in a frenzied match of trying to solve 30 math problems the fastest. But this feature isn't that great unless you have more than two people playing.
The game uses pretty much all of the DS's features. One test has you saying the color of different words that spell out a different color than the one you're supposed to say, and the game has trouble understanding the word "blue". And many activites have you frantically writing letters or numbers on the touch screen, and frantically means messy, which means the game could have trouble reading your handwriting, but I haven't had too much trouble with this.
Other than that, I can't think of any reason you shouldn't buy Brain Age for the low price of $20. Unless you're totally against combining video games and productivity, that's a great deal. Especially considering the fact that over 100 Sudoku puzzles are included! This is one of my favorite DS games ever. You won't regret buying it.