This really is a nice start for a classic, rpgmaker exploration/puzzle game. I really like how you used the setting, music, and sound effects to create a calming, empty, intriguing, yet slightly disturbing mood all the way through. The puzzles weren't hard, and they help move and set up the pace very well. Although, when they were tricky, I wondered if I discover a new bug or if I broke the game or not, since it's currently a work-in-progress. (This happened in a puzzle for a different rpgmaker game I tested; I did not find any bugs in your game fortunately.) The backdoor placement is, however, not very obvious, since the path from the toolshed to it is overgrown, but I think most players can figure it out.
Honestly, when I first saw the blood after discovering the lighthouse, I did not expect it would be that kind of game. I feel like the lore in the demo so far makes it seem like it was a summer home that a family never went back to for a long while due to tragedies from war or illness, kind of like what happened in Virginia Woolf's To the Lighthouse. Solemn and melancholy is what I am getting from this game, not full-on horror. Even the ghost which appeared seemed too playful. I hope the blood is there to suggest that there is a tragic backstory with the family, but that it isn't anything horrible or disturbing. But that is just me hoping; you can take it to any direction you want.