I really do like the idea, the well-done atmospherics, the foray into experimental platforming, the malevolent music, and so on.
However glitches and bad physics make this difficult. Drawing shapes does not always seem to register, and it seems I got stuck on the third or fourth level (forget exactly) in between the edge of the seesaw and the cliff. [R] should restart like virtually every other platformer for occasions like this, or simply wanting to restart. Drawing objects inside solid areas can produce some weird effects and maybe should be blocked in the first place. On the level with the boat, I'm not sure if there is some new shape to be drawn or if you intended two squares to cross. If the former, that should be made clearer.
Finally, when I came back to the page from playing earlier, the progress I made (completed a few levels) was wiped and I was put at the beginning. I tried playing again then hitting Pause -> Exit but even then it was not saved! You should fix the save feature or you may have some disappointed players on your hands.
I'll look forward to an updated version in the future, but at the moment all that and the shaky physics are putting me off.