I played through a few levels and I assume that when the game didn't go to the next level, that was it. It was fun what I played but figuring out what to do at first wasn't the best
For controls, the mouse wheel rotates the mirrors, the arrow going towards the mirror is the input and the arrows going away from the mirror is the output, putting light to any side outside of the input will result in the light being absorbed!
On a technical note, when I tried to load the exe download in the itch app, nothing happened, launching it outside of the app brought up a box complaining that UnityPlayer.dll was missing, the zip version worked fine