Just strip off the artsy-fartsiness and you're left with a platform game in which the character has triple jump and gliding capabilities. For each level, after you get to explore it a bit, eventually you come across 3 items. You then have to retrace your steps back to the start of the level, but you have a different set of rules (go back quick, don't touch the darkness that suddenly covers most of the level etc). It's this last bit that made the game interesting for me really; you can replay the game with different choices each time.
I'll admit that I'm not exactly sure how much of the game is altered depending on your choice, but it's a very interesting concept I think, and requires some skilled level design.
Anyway, nice gfx, above average mechanics, nice innovation and the music was alright too.