Help, I accidentally turned the game off in the middle of my event!

As the organizer, you can turn the game on and off any time you want. There is no “start” or “stop” to the game other than the game is on or off. For your players, once you turn a game off, the next time the player changes the tab or opens the game, they will receive a “game is off” notice which will remain until you turn the game back on.