I typically carry 9 DS games with me (1 in the DS and 8 in a little case I have). One of them is always Mariokart, since it’s one of those game that’s fun almost any time. It would take a great game to unseat Mariokart from its perpetual place in my pocket, and that game is… the sequel.
As would naturally be expected, Nintendo is readying another fantastic entry in its iconic kart racer. We don’t know any specifics yet, but we can likely expect a buncha new tracks, and a buncha old tracks. Also, there are rumors that Mariokart 3D (not its official title… yet) will have a built-in track editor, letting you create any track you can imagine (to a degree, of course). Sounds like this could be one of the games that spends the next 5 years in my pocket!