Okay, so I have to fix the mouse somehow on the game screen. Unity has probably a feature for this issue. I will look for it.
I encounter the 'black' you were talking about now by myself. This seams like a render problem with high float numbers. For me the 'black' only appears, the farther away I go from the center. Perhaps I can fix this, if I reduce the length scale of everything.
That sounds nice. Yes, it is a slow-paced relaxing game. Definitely not a pace like in shooter games.