The icons mostly describe what they do. Press start to start the timer and see the theme. Then trade devices with your friend and rate theirs. But if you are on computer than: Space to start. B to stop. V to delete all. N to erase. H to paint bigger. G to paint smaller.
Scratch for the pen code and me for everything else. Best played with multiple people. If you just want to paint then go here: https://scratch.mit.edu/projects/865879503/