A Pen created at CodePen.io. You can find this one at https://codepen.io/mtHuberty/pen/gXKExe.

Logical clone of the original Simon game. Toggling strict mode on will cause the game to start over on a missed button press,
otherwise the game will replay the previous sequence for you to try again. 20 points required to win. 

Missing from clone: incremental speed increases at turns 5, 9, and 13. 

In the future I may add an unlimited mode where the game never ends, but I would only want this available when in strict mode
to keep the challenge interesting!