brainage is boring for me. try animal crossing wild world. it keeps my sister busy everyday. she loves it, and if i were the video game person, i think it would be pretty cool. you move into a new town where your neighbors are all animals, you have to get a job at the local store to help pay off your loan. you can collect furniture, particapate in activities, make friends with your neighbors, donate to the museum, and much more. my sis actually let me borrow it one time and i played it for a few hours.
some other games she likes are:
Harvest Moon, New Super Mario Bro., Mario and Luigi Partners in Time, and Cooking Mama. Enjoy.
Elite Beat Agents, a very fast and compelling rythmn game that averages from critics a 89/100 rating and popular amongst nintendo ds users, it is possibly the best nintendo ds game out there, and its endless fun, uses licenced and music found in game, such as a personal favourite of mine: Canned Heat By Jamiroquai, i highly recomend Elite Beat Agents, its a fun and easy way to kill time using the ds and its just fun XD.
Pokemon diamond/pearl.....nintendogs...if you like racing mario cart.....if you like using the touch screen get Wario Ware Touched. My personal favorites are pokemon diamond and wario ware touched....but thats just me....i'm weird.
If you're a fan of Brain Age, I would recommend Brain Age 2, which is coming out soon. Elite Beat Agents is a very easy, absolutely fun game to understand, but can be very difficult. You may also like Tetris DS. Also New Super Mario Bros. And probably one of my favorite games on the DS is Clubhouse Games