I was a little confused when I was the purple ghost. I removed the box, but the message didn't go away and it wouldn't let me return to my human form. I had to re-possess the green ghost and then go back. Also I have no idea what that weird blue diamond outside the walls was.
That said, it's a good base for a puzzle game. And while the assest were pre-existing, I like the general vibe of the game.