I just 100%ed (or rather 1000%ed) Castlevania: Portrait of Ruin, both the main mode and Sisters Mode. (Technically you can't get the final two rooms in Sisters Mode, but whatever.) I started a playthrough as Richter, and I do love playing as Richter and Maria, especially Loli Maria from Rondo of Blood, and getting to switch between them with the press of a button is really cool. That said, there just isn't enough new content, so I might not bother to beat the game as them. And I don't think I have the patience or will to unlock and play Old Axe Armor mode, either. I feel bad because I 100%ed almost every Castlevania game, but I already gave up on Lament of Innocence, where I only did the main mode and didn't bother with the extra modes. Maybe I'll try to go back and do Joachim mode, but I really hated Lament of Innocence. Also just now I'm realizing I accidentally skipped Curse of Darkness. I guess I'll have to do that before Order of Ecclesia. I wanna beat every Castlevania game, and I guess while I might skip some of the extra modes, and I'll try to do any that have their own stories.
Also I skipped Vampire Killer for MSX but I tried to play it. That game just seriously sucks balls. Great ideas, but not executed well at all. And this is coming from a guy that loves Simon's Quest. I wish somebody would try to port Vampire Killer to the NES, give it the controls and physics of the original Castlevania. Then it would probably be good. Also give it infinite lives like it was clearly supposed to have.