So this forum and topic is specifically for discussing and playing the original Diablo 1 as developed by Blizzard North. I've also added discussion for Hellfire as well even though it is non-canon and Blizzard North (and South) were against it and not happy it was released. However, Blizzard North and South did have high level oversight into the development process for D1: Hellfire and provided some guard rails for what is and isn't allowed to be added to the game, which from what's documented here by Fandom, Synergistic Software mostly followed. However, "mostly" is the keyword here since they still added things that Blizzard North / South didn't want including some easter eggs. But either way, due to Blizzard North and South still play testing it and having Executive Producer status in the game, even if they didn't get everything they wanted, and Synergistic Software still slipped in their own stuff, I still believe that Hellfire is still worthwhile to be experienced, played, discussed, etc, even if it is non canon. Lastly, Hellfire was based off Diablo 1 v1.04, so any bugs that were fixed in Diablo 1 [1.05 - 1.09b] most likely still exist in Hellfire.
On a side note, if y'all don't really care about running the same exact source that was provided by Blizzard North and Synergistic Software for their respective releases, I feel that the Devilution/X project started by my friend GalaXyHaXz is still highly appropriate and you would ultimately have a smoother experience playing that one. I'm a sucker for playing the original game with the original files (even if it has bugs lol, but that's just me!). Feel free to use it and still chill on the forums and talk about D1 .
- DevilutionX (Preferred) - The continuation of the project where it uses Devilution as a base, but then includes a lot of QoL (Toggable via a configuration file). You'll most likely want to use this one. I linked the Devilution link above for completeness.
- Devilution - The core reversed engineered code that still keeps the bugs and all of that (Historical Archive).