We have all played naughts and crosses (or Tic-Tac-Toe if you'd prefer) at several times in our lives. And I am almost certain most of you will have used it in your class.
Well, Octo-Naughts is a similar concept. Except one team are octopi and the other are astronaut helmets. And they need to get eight of their piece in a row to win, not three!
Ask them a question, if they are correct have them come up and touch the octagon they want to inhabit. If their team has chosen to be octopi they click on the left side of the octagon, the right side for astronaut helmets. If they accidentally click on the wrong side, they can touch the icon that appears and it will disappear.