Adventure games ARE mainstream. Prof Layton was THE MOST popular title on the 3DS when it launched. In fact over 10 million copies of Prof. Layton games have been sold. The Ace Attorney series has sold over 4 million copies and is one of Capcoms best selling series.
Lastly, May 2011 was one of the worst months for Video Games sales - the only bright spot - LA Noire sold over 800,000 copies.
I've been playing these games since the C128 in 1985. We had one main publisher (Infocom) and a total of approx 26 adventure titles published over the life of the platform. Today, I can find 26 adventure games for the Nintendo DS for sale in the average store.
I did hear that only 12,000 copies of Gray Matter were sold on the PC worldwide. Anyway, back to playing Hotel Dusk - which shipped 230,000 copies in Japan alone.
