I love Sudoku and it's variants, and I think this is a great idea. I wasn't sure how to place the elements so I just solved as much as I could of it in my head. It was challenging and fun!
Thank you for the feedback. Right now, you enter with the num pad [0,1,2,3,4,5,6,7,8,9] or the buttons on the screen and left-click on a blank cell. 0 equals a clear cell, 1 equals light, and 9 equals dark. Currently, there's a bug in my code where the signal from the button nodes is not connecting to the cell nodes, which doesn't allow the cell node value to be updated when the button is pressed.