Oh man... that X sprite is wonderfully done! I want to see more projects like this one and Corrupted. Projects that take what exists and improve upon it in just small, but important ways. You even kept the running animation pristine, which I'm particular towards because X SNES sprite is one of my favorite running animation loops in all of videogaming.
Should make this multiplayer like an mmo-lite. There was a really cool animation on Newgrounds a 100 years ago that featured an SotN game but was played by multiple people, and at the end one of the players had chosed to become the next Dark Lord and fought the other people. It was a really cool concept.
My only criticism is his walk animation. I know it's the same from the game, but the difference is this one bobs up and down, but in SotN, he sorta "glides" across the ground and it felt intention to highlight his superhuman vampiric grace.
I know how to fix this too. There's one frame of his walk animation where both feet are off the ground by 1 or 2 pixels. It's easily fixed if you just move the sprite up on that frame and add that small space in between so they line up.
I hope that one day the source code for the PS1 version of this game gets leaked (or reversed engineered) so that we can have a SotN modding scene like the SuperMarioWorld or SuperMetroid modding scene.