Ok, so Alucard, Richter, Maria, Shaft, Succubus, Death, and Dracula are playable characters. Wonder who the shadowed-out 8th character is? Master Librarian?? Galamoth? Or maybe it's random select?
Wonder if the other characters equip the same items that Alucard does. It seems like you're only allowed to select one item at a time that boosts a given statistic. Seems like the weapon slot affects attack power, the shield slot affects defense, the body armor slot affects stamina, the head slot affects intelligence, accessory 1 affects luck, accessory 2 affects strength, and i'm not sure what the cape or legs slots do. That's an interesting way to do it.
They seem to have different attacks at their disposal. Also, the different blocks seem to represent different elements. "Green" blocks seem to be lightning, and I'd guess red ones are "fire", white ones are "holy", purple ones are "shadow", and blue ones are "water".
They have some odd playing card system with "crosses" (good guys) and "skulls" (bad guys) being the two suits card has a different Castlevania character on it (they found a new way to censor the Succubus). The cards look pretty good, I want a pack. I clipped them at wikia if you want to take a look: http://castlevania.wikia.com/wiki/Castlevania_Puzzle:_Encore_of_the_Night#Playable_Characters
Oh, and story is just a retread through SotN, nothing new shown at least, though I imagine they might have "alternate" events if you pick characters other than Alucard, which could be interesting. Maybe something to make up for the fact Richter and Maria had no storyline in SotN?? It'd be sad if only Alucard has a story and RPG mode, but possible.