I've been reading a lot about the Romans & from what I've gotten out of it, WEP must've took the way of the Romans & decided to make Doom greatly resembled them with the arena games, slaves, concubines, & the fact they invaded other provinces, countries, whatever. The Romans were all about power, which very much reminds me of Planet Doom.

I can even recall Zarkon's robe coming from one of the Kings, but I can recall his name.

Kyence has a section on her site about Zarkon's origins, tying it to past rulers and noting similarities in wardrobe and name and such. You check it out, it's an interesting read.

I agree that the Doomites had quite a bit in common with the Romans. Their gladiator fights, attitudes toward slaves, conscription for the armies (especially as seen through Joran's point of view in "The Traitor") is very similar to the Romans. Also their polytheistic nature; although we never hear the Doom gods named, Zarkon does refer to the "evil gods" in that remark recently brought up in the quotes thread, so we can infer that their religion has multiple deities.