I don't strictly need hard, and have been known to enjoy a Kirby game now and then. That being said, when I want challenge, I like it hard enough that I can beat a task/challenge/boss/level on the first try, albeit just barely (or harder, if the game is quick enough to get you back where you were like Super Meat Boy). I don't generally rage at games that are too hard for me, but I do tend to have a short attention span for games, so if I get stuck I usually move onto something else and don't come back for months. If I can't beat a boss or level after about the fourth try, or solve a puzzle after about an hour, that's usually about where I get bored and find another game.