Over the past many sections we have detailed at least six different versions of "Empire".
Should they all be called "Empire" and thought of as one entity or are they something else?
If anything, Empire was an evolution, with some branches leading to a surviving species, Empirus Fourus, and some extinct branches that grew too large like Empirus Three-D-us or Empirus Conquestus or Empirus Maximus. All are inter-related and all had some value and met a particular environmental requirement in their all-to-brief existences.
Now, there is a healthy word, dis-ambiguation. Let's leave the large work to Wikipedia and historians as whoever would have the energy to do so. I'll only mention some passing references as I became of various alternate Empires.
Some time after Empire 2 (or 3) had been available for play, I ran into a high school classmate who told me of a game called Empire that he played, if I recall at a university in Florida, that ran on a mainframe system and was submitted in batches, probably on punched card.
You made your move or moves for a particular step, then waited for a listing to be provided, often next day.
He asked me if that was the same as the Empire I had written. I told him it wasn't and described the game. I got the impression he may have not fully believed what I was describing, since interactive systems like that were generally not available and certainly not with graphics. One could interact on a teletype or, now, text CRT with BASIC programs, but NOT graphics. I tried to tell him it was real. Often, seeing is the only way belief is won.
Since then, a variety of Empires have come out. It is, after all, a powerful word, conjuring up so many aspects. I have seen commentaries of outrage that someone would use the same name as their game, even though PLATO Empire had existed ten or twenty or more years prior; they just hadn't heard of it.
PLATO's impact on the world of computing, from influencing many  , many designers of various systems, to the direct influence on the future of computer game design should not be some obscure, unknown history.
:Atari did, after all, have a login on PLATO and would have seen games like Empire and Panzer and Airfight and Dungeon and DND and Moria and so on.