Use u to turn the top face, e to turn the middle layer and d to turn the bottom face. Use right and left arrows to rotate the entire cube. Press space to randomly scramble the cube. As soon as you rotate the cube or do a move, a timer will start. When the cube is solved, your time will be displayed until you rotate the cube or do a move.
Look inside, I couldn't resist using a hacked block... No, I did not use a "pick random 1 to 10" block to make the timer accurate to the nearest quadrillionth of a second. Fully 100% pen, including the timer and the black background.