This is exactly the type of puzzle game I really enjoy and one I can see myself coming back to when I need to relax while keeping my mind engaged.
The level progression felt good. The signs in the early levels gave you just enough details to help you understand the mechanics without being overbearing. The levels felt like they built on each other, teaching concepts in a natural way. I played through every level. There were some that made me stop and think, but the solutions all made logical sense and it felt good when I solved them. I thought the branching paths were a nice touch, because it let you explore slightly different ideas on each path. The additional puzzles at the end was a great way to show off some of the other puzzle mechanics and makes me excited to see play the finished game.
The story was charming. I liked getting to help free the tormented souls. The art style fit well for the game. It was cute without feeling overly so. The different things you could interact with were clear and easy to tell apart.
I think the biggest thing I would have liked was being able to use both the arrow keys and WASD to move. It didn't feel bad to just use arrows for movement, and remapping meant I could have set movement to WASD if I wanted to, but I do tend to like having the option for both in these types of games.
I am really looking forward to the full release of this game. The game currently is a great length for a demo, but it also left me wanting more.