The game should ensure that at least 1 solution exists on the chest levels. I dislike having to redo an entire level because there was no way to open the chest first time around.
You should use the bounding box of the symbol for the target of the mouse click. Right now it is too easy to miss if your click doesn't hit one of the lines on the symbol.
It is a beautiful game, but it is in need of more and more varied gameplay. There was obviously great care put into this and it's a shame to see it fail to live up to its potential.
Desperately needs a way to reset a level. That way even if things get messed up (as they will at this point in the design process) the tester isn't forced to reload the page. I found myself hopelessly stuck in a wall on the second level, the attack button seemed to do nothing and I'm unsure what the blue number at the top of the screen means. Keep at it and I'm sure these problems can be overcome.
As many previous posters have said, it is far to easy for a single slip to ruin your attempt. This isn't the sort of difficulty that most people find rewarding to overcome. Basing the score on time taken might be a better choice. Minor mistakes would still cost the player, but not necessarily force a reset if the player is quick enough and can see the solution.
Already, I commend you to do 4. I try to make games based on feelings, emotions only. My goal is that the tree seems a mirage exciting, but difficult to reach. I hope that the experience will not be too displeased you.
There are major problems with the controls. I can't beat level 2 because most of my L shapes are rejected. I Like the concept, but right now I find the game unplayable.
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I am adding new levels and enemies, and have plans for a final boss fight as well. Thanks for checking out this early version!