A-Train DS, or A列車で行こう DS, a Japanese game about managing trains. Basically like Transport Tycoon/OpenTTD, but focuses on Japanese train. It was actually really good, it actually made me obsessed with Japanese trains. Coolest thing about this game is, you can actually "ride" the train you built. It was like a dream come true for childhood me.
Yet, I rarely heard anyone online talks about this game. I really recommend others to play this game... If you can read Japanese as I am not sure that there is English translation for this game...