Just because people dont seem to know this- but LoS was always intended as a Castlevania. It wasnt "retrofitted" the name, or decided on later.
Its level of "differentness" however is a result of Konami not being able to make up their minds on it. It started a CV 1 remake. Then became an original Castlevania story. A reboot. Then Konami told them, keep making it, but drop the Cv name and name it simply by the subtitle, "Lords of Shadow", making it an original IP. when the initial teaser was released titling it as Lords of Shadow, konami would see what the reactions were and then make a final decision. Eventually they decided, "Ok, it can be Castlevania again".
This back and forth is IMO, is the reason why it feels like Castlevania in basic form and function, but at the same time, is COMPLETELY different from Castlevania.
Im most certain that had this idea of changing it to an Original IP hadnt come up, it would be more castlevania like in the eyes of fans. it might even have had that music Cox promised us.