Limitless game/program for DS Lite?

I am looking for something for my DS Lite that I won't finish in 2 weeks and be bored with. I hate games that you can win and be done with. Something other than a clic game with levels would be good. Internet or something? I already have MySims, Brain Age 2, Cooking Mama, and Nintendogs, which I see are quite popular. Any suggestions?