Well, I don't want to say too much because some of the plot is still in development obviously and nothing is concrete.
But, it's a completely different main character. Whereas in the original, the player is Lydia Snow, a teenage girl targeted by the cult, the sequel will have you playing as one one of the police detectives assigned to the case once the cult was exposed. The story is set four years after the original game and since the MC has experience with the original case, he is put back on it when reports of unusual activity start showing back up in Daphne.
All the characters from before, assuming you had a good enough ending to survive with your free will in tact, have moved on with their lives as far away from Daphne as possible. Although there will be cameos from these characters and plenty of information on them and what happened, it is in a sense a fresh start character wise.
Whereas in the original, I focused on the plot being that you, the MC, have to solve the mystery in order to save yourself and your family, the sequel is more the case of 'from the outside looking in'. In depth info about the cult, it's origins, and actions from a detective's point of view is what I'm going for this time around. You still have to solve the mystery, but the circumstances have changed. The cultists aren't just rural townsfolk giving in to the control of a demon to save themselves, it's people coming out from the woodworks to converge on the last known site where the demon was summoned and served. People who have dedicated their lives to serving in this cult. They are organized, smart, and very well hidden(plus a hell of a lot more dangerous). Just like in the last one, you will have increasingly frightening nightmares the more exposed you become, you'll experience increasingly heightened paranoia throughout the story, and eventually all of your choices will lead you to one of the 9 endings.
Obviously, this is all just the bare basics I have so far. The choices, variables, and some of the fine details of the plot are still being mulled over. That's the main reason I was wanting some criticisms. I want to know what people did and didn't like about the original so that I can make the sequel an even better(and more frightening) experience.