Casual games is a pretty vague term, but I understand it to mean games that are specifically designed to people who haven't played much games before. FPS is one of the oldest and most established genres in the West, so I wouldn't put it in the category.
Of course it does feel so sometimes, especially from the point of view of someone who plays strategic simulations and Rogue-likes. How dare those guys who only play games with 5 second attention spans call themselves hardcore?!?!
Alas, that's not what the term means, and FPS games aren't all brainless. Stuff like Halo and Call of Duty are definitely mainstream by now, though, and I don't think they're particularly hardcore either.







