Here's a rant about something I'm not even sure has happened more than once. But I'll assume it happens a lot. I remember talking to someone about the game Doom, and they wondered "which Doom I meant"... Maybe they asked because there are multiple "Doom games" in the "Doom franchise", or because "Doom II" also is called Doom (plus the two I's at the end), or because a 2016 game in the Doom Franchise is simply called "Doom". However, my answer is simple: I meant Doom, the game from 1993 that is called Doom.
Here's a message to you who say "Doom" and mean the series, the sequels or the 2016 game:
Doom (the 1993 game, I'll clarify in this sentence only!) doesn't become "Doom 1" just because the sequel "Doom II" gets released. It neither becomes "Doom 1" because the games turn into a series and the series takes its name. It neither becomes "old Doom", "classic Doom" or "1993 Doom" because 2016 Doom exists and takes over its name. Doom came first and has all the core ideas that make up the sequels and the series. The sequels and the series are completely based on Doom, and not just games that happened to come after it. The most Doom thing of all the Doom things in the world ever, is the game Doom. It deserves the name Doom, not just because that IS its name, but because it deserves the name so much more than the 2016 Doom.
This rant doesn't mean that sequels can't be more defining of a series than the original. But in Doom's case, they can't. Because the original is so good that it deserves to never lose its name and become "the first game in a series". I can't stand people talking about this masterpiece like it's a prequel to the 2016 game, like it's that weird unpolished "first album" before they could afford a real studio and make their REAL first album (think Power Metal by Pantera. lots of Doom songs are based on Pantera, so this parallell is okay).
People talk about Doom like it is an old game that revolutionized 3D and had a retro look. Yes, all that is true, but the fact is that it revolutionized 3D, looked great back then and still looks great, and hasn't been surpassed in quality by any other game since it came. It wasn't just a start, the first trembling steps, of a great thing. It was the great thing. People who view it as "classic Doom, a great retro game" don't seem to understand this.