To me, a "hardcore" game, if you wish to call it thus, is one that requires patience and effort in order to succeed with it. It requires you to learn how it works, and then respect how it works. There is little to no hand holding involved, and it lets you figure it out for yourself. That's the theory, anyway. I don't put much emphasis into it, I just like to get lost in a game and to feel accomplished at the end of it. It's hard to feel rewarded in a game that holds your hand all the time, or always tells you where you have to go.