Nintendo DSi XL - Midnight Blue I originally bought this for my son, I tried the built in Brain Age and got hooked on it so I bought my own. It's very addictive and gave me a slight headache going through the tutorial modules. In the beginning my brain was tied to 64 years, but after 2 weeks of 30 minutes of training every day I became a teenager of 25 in math and 21 in arts and literature. Since our brains start to deteriorate after our 20s, the age of 20 is ideal for the brain. If you have a DSI or DSI XL with Brain Age built in, I would recommend that the child/children exercise daily. The more back-to-workout stamps you earn, the more programs open. It's a lot of fun and my brain shrinks with age. FYI, there's parental controls that let you turn off Wi-Fi or set rating limits on games that can be played on the device.