All four of the Underworld movies are rated R. They contain graphic violence, some language, and 2&3 contain sex/nudity.
First was Underworld, Then Underworld Evolution , and finally Underworld: Rise of the Lycans but in cronological order it goes Underworld: Rise of the Lycans, Underworld and then Underworld Evolution
No one knows this. The first film was written as a stand alone. It was successful so they continued writing sequels. They will probably continue making more so long as the franchise is making money. That's how most b grade movies work, if you look at franchises like Friday the 13th or Nightmare on Elm Street; these movies were not written with the intent of making dozens more. They just make one movie and if it does well they keep inventing more.
They kissed once in Underworld, but in Underworld: Evolution they kissed AND had sex.
"Underworld: Evolution" (2006)
Selene - Underworld - was created in 2003.
Underworld - 1999 is rated/received certificates of: Ireland:15
London's Underworld - 1914 is rated/received certificates of: UK:U
Underworld Histories - 2006 is rated/received certificates of: Australia:MA
The Underworld of London - 1915 is rated/received certificates of: UK:A
Eyes of the Underworld - 1942 is rated/received certificates of: Sweden:15
Underworld Histories - 2006 Montreal is rated/received certificates of: Australia:MA
Underworld Histories - 2006 Tijuana is rated/received certificates of: Australia:MA
Underworld Histories - 2006 Chicago is rated/received certificates of: Australia:MA
Underworld Histories - 2006 Boston is rated/received certificates of: Australia:MA
Underworld Histories - 2006 London is rated/received certificates of: Australia:MA
Underworld Histories - 2006 Philadelphia is rated/received certificates of: Australia:MA
Underworld Histories - 2006 Miami is rated/received certificates of: Australia:MA