Is this level beatable in the demo. I sit for halve an hour on this level now and have no idea. Seems like there is only one to two options per step and if there are two, one of them is a guaranteed dead end. Like the demo pretty much so far but this level i can't beat. ...

Is there any visual clue in the level select, if a level has been solved by you? I think I solved all levels, but I can't really see, if I have forgotten to play any.