An add-on pack for the original Diablo, by Blizzard. It added several new elements to the game, not all of which i totally liked. The Hellfire pack unbalanced the game slightly, and it did not solve many of the issues that made Diablo 1 a lacking game (besides the rampant multiplayer Battle.net cheating).

First it added new character classes. The only "normal" add-on class was the monk. He was good without a weapon, and excellent with a staff. The object of this character i was never sure of, but it was fun from the perspective that i had played the game many times before, and could use the change. His power was Search, which found items that one would have normally missed. This drawback of the Diablo item system was fixed in Diablo 2, by making all items of interest available and easy to click on with the ALT key.

Two other characters were included, but they had to be unlocked. By placing a text file, called commands.txt with a few switches in the directory with Hellfire, it would unlock the bard and the barbarian. The bard was the most unbalanced, because she (it was a female character model) could use two weapons that always hit, and had the identify scroll spell as a skill (meaning that it took up no mana to use). The barbarian could use no magic, but had an insane amount of strength. Fun if you wanted a challenge.

There were minor additions to the game system. Runes (almost identical to scrolls) were added in as an afterthought. Among spells, apocolypse was now available as a book; very handy for those of us who played wizards in the original installment. Oils came out and had some weird permanent effects on weapons and armor. (Oils are replaced with "socketed" items and gems in D2).

All in all, Hellfire was good for the veterans of hell, who wanted to see a new face on their characters, however, for the mainstream populace (ie: those who left their rooms on the weekends), the add-on did not provide much to what is, overall, a masterfully done game.