Good to hear that at least there some challenges with the newly implemented nightmare mode.
I think it really depends on how one play the game with melee in nightmare mode. And its quite normal to equip a bow and shoot an arrow to pull a mob or two out from the group to finish them off with melee attack, which I dont think is against playing as melee. Even well equipped, charge blindly into a huge group wasnt a wise choice to me, unless one enjoy spamming potions non stop, or really being stuck in some small room, eg like boss fight.
Guess I will restart the game again in nightmare mode once getting my hands back on it with the new patch. Should be more fun.
