Welcome to the forums! Your emphasis on the occupants of a haunted house and their stories—stories that the MC can influence—sounds like a fantastic idea. I played the demo a couple of times, and I saw a few possibilities.
The only change I think you really need to make involves the suggested names for your third gender option. When I chose not to specify my gender, I was given a list of male names. Players who want a nonbinary character will pick that gender option, and might find the names offputting. I suggest unisex names from whatever time period the MC was born in (Sam, Frances, Billie, and so on).
One major change I think you might consider is cutting a lot of the stuff about the MC’s parents. Are the parents going to come back? Are they coming back soon? If not, I would cut as much as I could, leaving the parts where the MC discovers the in-game ghostly powers. Then I would rewrite those parts so that the MC discovers those powers by interacting with the Bonaventures instead.
My reasoning is that the most important characters should be introduced in the first act. There won’t be any significant progress or character development here until the parents leave. Meanwhile the Bonaventures, the people I’m supposed to really care about, are waiting in the wings.
On the subject of death: One thing that ghost stories seem to have in common is injustice. Someone murdered the MC (my money’s on the father). Or the MC was in love, and that driver shouldn’t have been drinking. Or a mean-spirited prank went too far. A ghost is someone who lives on because accepting such a wrongful death would be too much to bear. It wasn’t apnea (but maybe everyone thought it was apnea…)
How the MC died could arguably be more important than whether it happened in the house. Another thing about ghost stories is that the death is what defines the ghost. That’s where the motivation comes from. It drives the character. This demo felt a little flat in places, and I think that might be why. I was playing a pointless ghost, and the ghost knew it too.
I’m not latching onto Lucas because I want to follow an accountant around for the next 60 years in the hope that it will somehow be less boring than being alone (oh God why can’t I die). I’m latching onto him because I cannot rest until a great wrong has been righted.
If I help yet another overerprivileged college kid solve his personal problems on the way, bully for both of us. (Oh, you’re worried that you’re only becoming an accountant because your lack of confidence is holding you back from taking risks and pursuing your dreams? That’s a tough situation. Almost as tough as when my father suffocated me and got away with it by making my slow, painful death look like sleep apnea! But too bad about your feelings. I guess that’s life for you. Jerk.)