Well definitely an interesting twist on mirror puzzles. Not entirely what I was expecting, but was a fun game to play through. I wills ay there was not a lot of feedback though.
For example clarification on which side was outputting, how the buttons fully worked etc. it was a little vague sometimes and I feel like maybe having the emitter be a different color could help with that or something similar.
Also one other thing I would say is that the dice were quite big when picked up which was a little hard to then check their sides where moving them around. I think maybe making them get added to a bag or something similar that you can pull them out and rotate normally could help. Although it depends.
Speaking rotating normally I ddi mention it while I was playing but for reference I think maybe having the control scheme for rotating them be Q/E for rotating the die left and right and scroll wheel for forward and backward. It's a little more moving a round, but I feel like it would allow easier messing with it. Though that may just be me, and it may still be worth keeping the current one and allowing for both.