It's a very nice concept.
I have a big complain. This game should run in any kind of PC. I find a very big slow motion when watching the mountains/sky in the Moth Forest (when Im inside of water caves it runs almost normal and when I'm at the top of platforms when I can't see the mountains/clouds, it runs almost normal too). I have an ATI 5770 and an Intel Core i7 4770... so I find it really odd this kind of behaivor.
It's not exactly an fps drop, because the game slow down itself time.
Other thing that seemed weird to me, it's that I couldnt change the game resolution (maybe demo has a fixed res ?). I was running it at 720p when I have a 1080p monitor.
I liked very much the game, I'm probably buying it.