Comparisons between Rome in the first century BCE and the United States today have become a hoary, moss-ridden cliché. By the time of Marius and Sulla, almost two generations before Gaius Iulius Caesar became dictator for life, the Roman Republic had already become a de facto empire that maintained only the forms of representative democracy. Meanwhile, opposing gangs of Optimates and Populares staged bloody rumbles in the streets almost daily. Historians can argue for days about whether Caesar and his allies did Rome a favor by hastening the demise of the decrepit Republic.
We keep coming back to that word "Republic." It's an incredibly important concept. The majority of nations today keep the word in their official names, deservedly or not. Even North Korea is officially "The Democratic People's Republic of Korea."