Beautiful game, very good ideas, overall it's very very good!
However, sometimes I stuck myself and I just have to restart the level (for example, I no longer can grab the cube because it's under me)
It's sad, because it just happens when I try things.
I think you could resolve my problem only by giving us the ability to grab cubes right under our feet. This way, my problem is no more :D
Anyway, good job overall :)