While not a 'game' in the fun sense of the word, Brain Age is a valuable tool to keeping yourself mentally sharp.

User Rating: 8 | Brain Age: Train Your Brain in Minutes a Day! DS
Brain Age is definitely not the 'game' to get if you're looking for a fun time. It's completely focused on improving your overall intelligence, which isn't a bad thing, but isn't really terribly entertaining either. You can choose for a series of small tests such as reading aloud or addition in order to train yourself, then take a test to determine your 'brain age'. The idea is that, as you come back and train every day, your brain age becomes better and better. However, this sort of thing can only hold interest for so long, and after a while I found myself just using it as a high-tech Sudoku booklet. While the idea behind it is admirable and the talking head that guides you through your experience is cute, it simply isn't innovative to hold the players attention. If you have the willpower it takes to get yourself to train every day then this is a great game for you, but if you don't, you might as well just purchase a Sudoku game.