There are few boards in the Story Modes of Bomberman games that can hurt me, but I always liked playing it with a friend because that changes everything drastically.... typically the other person is not very good at the game, and you're not only concerned with killing enemies/destroying switches, but you've also got to watch out for your buddy and try to get as many extra lives as possible.  

You know, though, it would be interesting to try to determine what makes a certain board difficult. Enemy placement, enemy types, what items you can have at that point, level structure, they all play a part in it, but it would be neat to try to develop the most difficult Bomberman stage.... actually.... why haven't there been any Bomberman games where you can build your own stages?