Start with a group of your best friends or family standing in a line with enough space to move. Next, say "Alexa, open Simon Says". After a quick prompt, say "Start the game" and you'll be playing!
The rules are simple: only perform the spoken action if I say 'Simon Says' first. If I don't say 'Simon Says', don't do anything or you are OUT. The last person still playing the game is the winner!
Beyond that it is totally up to you if you want to add rules, make it more or less strict, or whatever else you want to do! Some people try to require you to maintain all actions at the same time (which is really hard!) and other people only want you to perform the last action spoken.