A cool concept, and a very good effort for your first game for someone new to programming! :)
A few suggestions would be to reset the cube properly when you press "R". If I was a sphere when I press R, I start the next round as a sphere. Also to show the player when the actions are actually happening (explain that every second the next action happens, or however it works).
Great effort, keep up the good work and good luck in all the future game jams to come. ;)