Ok, you know the fight between Alucard and Ricter? Are you supposed to beat him or do something else to him? I beat him, but got an unexpected ending

Yeah, this what you have to do. First you must get the Gold and Silver rings. I forget where they are so just use a FAQ for that. Once you have them, wear them and go to the green room with all the clocks. (where you first encounter the girl) The floor should move so go down and find the same girl and talk to her. She'll give you the Holy Glasses. Once you have those go to fight Richter but with the Holy Glasses on. When you have the Holy Glasses on then attack the Green Orb that is around Richter instead of Richter himself. Once you do that you have gotten the true ending. (and the inverted castle)