I don't personally like Hellfire, I mean it's alright, but it isn't by Blizzard and it just seems like a hacked version of diablo.

I'm playing Diablo 1 right now, sorcerer, I played through normal and killed diablo, I'm doing nightmare now.

Normally you can't even play nightmare/hell in single player in Diablo 1, unless you have Hellfire installed. But I found a difficulty editor hack that I'm using to change it to nightmare difficulty. Gonna play through Nightmare and Hell.