Wow, nice one! I think it's a good MVP project for mobile.
Few things must be polished at first, but i think it's almost a mobile-ready build.
Sometimes, when I push too hard, dice flew out from the cube and then teleport back inside.
Also, I would add a special effect for "spikes" appearance in another place, so the player would know at least 1 second erlier that "spikes" will appear in a different certain place (like in other reaction games). You also can use it later for difficulty levels, like if it will be 1 or 2 second in "normal" difficulty, and 0.5 seconds in "Hard" mode.
Overall very VERY well-made game! The visuals are great, and it would be nice to this game on mobile!