I've been on these boards for a while answering questions about SotN and one thing that kicked up my curiosity was that blurb about playing as Maria. I did a bit of research and it turns out that she's not a playabel character in SotN. I've seen her sprites, and there aren't that many. Pretty much all she can do is run, "hop" (i'm not even going to call it a jump) and stand. Those are definatly not enough sprite animations for a playable character.
However that dosn't mean that she's not a playable character in other games. On the PC Engine Game "Dracula X: Rondo of Blood" She becomes a playable cahracter after you rescue her. Some of you may remember that there is a SNES game called "Castlevania: Dracula X", well this is a watered down version of the PC engine game with a very much abridged story. You don't get to play as maria in the (rare) anerican SNES game.
The other game i know you can play as Maria in is the Japanese saturn version of SotN. You get to pick from the beggining of the game who you want to play as, Alucard, Richter or Maria, and if you play as Alucard, I've heard that Maria is also a boss you have to fight.