The Promise and unwinnable states (Spoiler for that section of the demo)
I played the first part of The Promise (before you get >!the rod!<) and was kind of amazed that there seems to be no way to "break" it and get into an unwinnable state at all.
Then I got >!the rod!< and after that it seemed that it was trivially easy to put the game into an unwinnable state which could result in hours of puzzle solving having to be restarted because you pushed a box into a bad place. (Obviously you can undo, but I'm talking about making a mistake and continuing on without realizing.) That seems unfortunate. It gave me anxiety and discouraged free experimentation like I would do in the rest of the game.
But at the same time, I was able to complete it without being soft locked, so maybe it isn't so bad. Maybe it's actually pretty reasonable in that you _can_ soft-lock if you do something silly like push a box into a corner, but you almost always know you've done the wrong thing and can undo right away. If you are able to make reasonable progress in an area, then you can reasonably assume you haven't soft-locked and can proceed. Which makes it a really clever design - but a very brittle and difficult to prove design. I would worry about increasing complexity of this section as it expands outwards in the full game.
Thoughts?