I get it - Casual games are built for anyone to get into and satisfy quickly. Hardcore games like RPG's only satisfy if your dedicated to the whole 100 hours of the game experience. Why is it that so many FPS games are so freaking easy then? not very hardcore really.... Still, I think theres a lot of "casual" games that have better gameplay then the "hardcore"
It's like Halo 3. It's easy to be good and have fun in the social matches when you first start out, but when it comes down to MLG in the hardcore playlist it's all about who can get the 4 headshots with battle rifle off first(which is the fastest way to kill someone with your starting weapon(Battle Rifle) in the MLG gametype in Halo 3 if you don't play it).
Anything with challenge really. There isn't a clearly defined line. It is obvious with some games- Gears of War vs. Ponyz, Resistance vs. Circus Star, but it isn't as definitive with others.
Ah yes the whole hardcore/casual thing has only come up somewhat recently. In reality there is only one thing to know. A game is a game nothing more and nothing will make it a casual or a hardcore as it is a video game and people will play it regardless. The only difference are the end users. Their are some who just feel as if it's the end of the world if they are grouped in with a gamer who plays a game they'd wouldn't want to play. So they have to consider themselves hardcore in order to feel better... or something like that. The only people who are "hardcore gamers" are self claimed "hardcore" nothing more. So really there is no game that qualifies as a hardcore game just like there is no game that qualifies as a casual game. They are all just plain old video games.