The dungeon where that difficulty spike happened was, in fact, one of the plot-sequence areas, something we haven't seen much of before. It was the exploration of the mind of a character - in the form of a cave. He sent ghostlike projections into battle - one of each character class - who were evenly matched to your player character by level. Unlike the dungeons between areas - the sewers and whatever - we were told that once this plot sequence is done, you won't get to visit it again. We didn't see much in the way of narrative storytelling either outside of a little text. It'll be interesting to see how Hellgate handles its story. Does a dungeon hack really need a story to be good? Nope.
What should also make the game enjoyable - really, a crucial element of this sort of game - is the ability tree you manage as your character rises in level. We got a peek at it; though we weren't able to examine it closely, we saw a couple dozen abilities, each with multiple levels of power which, according to the developer who gave us the demo, do change the effect of the abilities during gameplay. If there really is a lot of variety to it, that'll be a great incentive to keep playing.
