I, too, think I‘m getting a better understanding of the requirement...
1/ preference to retain safe (minimum) speed option as part of the game.
2/ requirement to stop all cars at the tap of a button.
And, if you are walking around supporting the kids at the same time... perhaps the button should be on a wireless fob. This should all be do-able using the bluetooth platform embedded within the ARC PRO... but I suspect it would need some professional help from an experienced design team...?