SFR said:
So... if first person shooters are the most casual (which most people would completely disagree with you with), then what is the most hardcore? Puzzle games?
No genre by it self is hardcore. Hell, no game is hardcore.
But I think we can agree certain genres are played far more casually.
And there are more "casual genres" then shooters.
Like the recent occurrence (see: plague) of Rhythm games using fake plastic instruments.
Puzzle games are pretty casual. Bejeweled on the cellphone for example
First person shooters are played by every one too. Which is fine. But that doensn't make one a hardcore gamer.
A hardcore gamer is an enthusiast who uses gaming as their main hobby and is knowledgeable about gaming's history. The hardcore gamer plays a variety of genres and seeks out new gaming experiences.
The hardcore gamer doesn't play it safe and is rare even on gaming forums.