I don't know if this is in the game yet, but you should add an option for local multiplayer. I feel like some way to ensure that it is done fairly so that each player can't see what the other is gonna do is buy blocking the entire screen with a prompt along the lines of "Press any button when you are ready" and will then bring back what you normally would see assuming the players have switched controls. An example of this is when you play Advanced Wars 2 with your friends locally and have Fog of War enabled.