I'm in the Desert now, and I was still thinking about my treehouse problem yesterday. I was thinking that I failed to answer the game's question in that one particular puzzle, which was'what happens when a star is alone'. I never put 2 and 2 together in that his companion can be ANY piece of the same color, it doesn't need to be a star. All along I ignored that his companion in the early puzzles happened to be another star.
It's so blatantly obvious that I didn't see it. I was so fixated on solving it my way, that I was ignoring the question the game was asking. Still weird that the tutorial panel for this concept came after the more complex puzzle, but that was probably the point.
Out of interest, what do you regard as the tutorial panel for the puzzle? I felt the puzzle after it reinforced the rule, but I didn't think it was inherently better at teaching it than the former. I might not be remembering right, though.