click to start. wait for the bottom lamp to light up, then click as fast as you can. click early and the round is void. five rounds, your average is the score.
click to start, then wait for the bottom lamp to light up and click as fast as you can. the wait is random, roughly 1 to 4.5 seconds. click before the light and that round doesn't count.
you get five rounds, and your average reaction time in milliseconds is your score.