Pretty cool! It took me about an hour to get through to the end and win, however, some of that time was fighting with bugs and misunderstandings - I ended up getting a pressure plate (in maybe the 3rdish area) stuck down, but the pillar not firing projectiles, and even after reloading it wouldn't fire. Eventually I completely exited to desktop and came back in, and it finally worked as I expected (but I spent quite a while wondering if my expectations were wrong ^_^). I also spent quite a while mapping out the first area with only the rune of Harmony - I would go in the dark area, step in the darkness until I respawn, then enter the light area, and made it quite far, and enjoyed the mapping, before I finally realized I must be missing something =).
I like the (mostly) non-violent puzzle solving, was pretty cool. And, for when there was fighting, thank you very much for keeping them dead/damaged/whatever across respawns, I don't think I could have done that in one life (I couldn't quite figure out if there was a trick to killing them, or if it was just "hit it until it dies").