Nintendogs was the killer app that got the DS a foothold in North America. Mario carried it forward a year later. The DSLite drops in the same year, effective but not mind blowing until christmas of that same year 2006. Then over the course of six months proceeds to sell more than it sold in the prior year and a half. At that point is was a combo of major sentiment, mario and nintendogs. I say good sentiment because the sheer volume of DS sales outpaced any of the games sold for it during that time. People bought the DS just to own the DS regardless of the games.